Karai is the rebellious leader of the Foot Clan, a master kunoichi, and the 16-year-old adoptive daughter of the Shredder. She is voiced by Kelly Hu in this variation. Karai was also revealed to be Hamato Yoshi's long-lost biological daughter, Hamato Miwa, in Showdown, Part 2 whom he had believed had also perished in the fire fifteen years ago. In Vengeance is Mine, she was inadvertently mutated into a serpent, but she retains some of her humanity and has partial control over it. She is a major recurring character in the show.
In her debut episode, New Girl in Town, she and Leonardo immediately have a similar relationship to that of Batman and Catwoman; as she tries tempting him to be more like her, while Leo wants her to see she's not as bad as she appears. Karai confronts Leo, who is separated from his brothers when he and Raphael have a heated argument over who should be their leader. During their first battle, she temporarily blinds him before attacking him. However, she leaves him alive. She later runs into him again in an alley and fights him again. They both exchange some banter and some blows until Karai holds a sword against Leo's throat, trying to convince him that he's not as good as he appears. She also notes during her fight with Leonardo that she understands the Shredder's revenge, but she's uninterested. And that, she jokingly stated, he (the Shredder) should get a hobby. She tells Leo to meet her at the top of a building without giving him any more information other than she wants to show him something. At midnight, Leo meets Karai on top of the building she informed him about earlier. She tells him that they're there to steal a famous katana, which is clearly visible in a museum window down below. Leo refuses to help her which upsets her. Before she takes out her katana, Leo stops her and tells her that he believes that there's good inside her. Raphael then shows up, and is angry at him for "holding hands with the Foot." Upon Snakeweed's attack, she stands there smiling, until Leo asks for her help. She throws her knife above the wall near his head and leaves; Whether this was to help him or not is undetermined. Karai meets with The Shredder, who is not happy that she let Leo live. She tries to talk her way out of it and say that he escaped, but The Shredder doesn't believe her. He tells her that she must kill him next time, or else... Their scene ends with Karai addressing him as "father". Her relationship with her "father" may be somewhat precarious, as she becomes frightened after making The Shredder angry at one of her comments.
In The Alien Agenda, Karai finds the Turtles fighting the Kraang. She becomes somewhat concerned over The Kraang, yet intrigued. When she informs The Shredder of this, she tries to convince him to take some concern over them, due to the mutations that happened to the Turtles, Xever and Chris Bradford. Shredder believes that this is all nonsense, and dismisses her suggestions. She becomes relatively disappointed that her adoptive father has no interests or concern over The Kraang. Shredder then reminds his daughter of his reason for his ongoing vendetta against Splinter. To find out more about The Kraang, she questions Leonardo when the two happen to encounter each other on a rooftop, during which she playfully flirts with him. But he refuses to tell her anything, warning her that the robots are dangerous, while also telling her to leave him and his brothers alone. Raphael asks Leonardo about her, and if they should tell the other two brothers about her and his "relationship", but Leonardo says that the two already had a 'chat' and confirmed that she's going to leave them alone. Raphael thinks that telling her to back off is a pointless idea. She keeps it to a point, as she followed the 4 brothers into The Worldwide Genome Project (which is actually run by The Kraang in secret) building, seemingly undetected. However, when the Turtles realize that Raph was missing, he has found Karai and pins her down. The two fight, but it's not long before Leonardo breaks up the skirmish. When Raph makes a comment, Leonardo argues that Karai is good, while Raphael thinks she's pure evil, while Michelangelo and Donatello are perplexed by who she even is. The fight gathers The Kraang's attention, and they attempt to subdue them. Karai makes the fight worse by unleashing a monster containing DNA from assorted animals. She then grabs a broken Kraang droid, abandons the Turtles, and brings it to her father to possibly convince him that The Kraang are worthy of looking into. Also, Baxter Stockman claims that he could work with the technology efficiently. The Shredder's mindset has successfully been changed, and he asks her to find out everything she can about the Kraang.
In Enemy of My Enemy, Karai appears out of nowhere while the turtles are surveying the T.C.R.I. building. She immediately pulls out her katana and attacks Leo, Raph, Donnie, and Mikey all join in to fight her, but she quickly begins to outmatch them. She mentions that she overheard Donnie talking about The Kraang. At first, they don't want to let her in on the situation, but Raph lets lose that they are trying to stop a full-scale invasion. Suddenly, a flash of purple light comes from the T.C.R.I. building. A door opens on a side of the skyscraper, and a strange aircraft floats out, resembling a jellyfish, with a round body, three short, stubby tentacles and a single purple "eye". It is piloted by two Kraang brains, who quickly spot the turtles and Karai and move in to attack. The ninjas run across the rooftops, narrowly avoiding the ship's energy beam weapon. Karai ducks into an alley, while the ship pursues the turtles. Leo runs out to draw the ship's fire, while the other three make it to the sewers. Leo joins them and they watch the ship from a storm drain. The ship activates a cloaking device and vanishes to avoid detection by a passing Police helicopter. Karai returns to The Foot's headquarters and reports what she has seen to The Shredder. He ignores the threat that The Kraang pose, and tells her that they will soon receive a shipment of new weapons that will end their war with the turtles and Splinter. Later, after a brief spar with Leonardo, she tells him that she wants to help them fight The Kraang. She is afraid that Shredder's stubborn refusal to see anything beyond his vengeance will get them all into big trouble. She asks him if they could work together, but Leo refuses and leaves. Later, the ship chases the Shellraiser down a street. Leo asks Mikey for an escape route and Mikey accidentally leads them into a dead end. The ship starts to blast through the Shellraiser, but they turtles narrowly avoid definite annihilation by backing out of the alley quickly and hitting the streets once again. Karai then jumps out of nowhere onto the top of the ship and effortlessly, begins slamming her katana on it. Leo decides to help her out, and he jumps into The Shell Cycle and chases her and the ship down on his own. When Karai falls off of the ship, Leo saves her at the last possible second. He then brings her into The Shellraiser. When Raph instantaneously objects to her presence, Leo tells him to hear her out. Karai tells them that they need her help and that the only way to take that ship down is with a missile launcher from the Foot shipment, which she tells them will be arriving at the docks the next evening. All of the turtles except Leo are suspicious of her, so Karai says that she will get the missile launcher herself. Leo agrees that, if she gets the weapon, the turtles will team up with her to stop the ship. Secretly, however, the turtles devise a plan to eliminate The Shredder, as he would never be expecting them to show up there. As Karai retrieves the missile launcher, she spots the turtles on top of a shipping container near the docks. She pushes her adoptive father out of the way so that the electric grenade (which Donnie invented) electrocutes the Foot Soldiers and the man with the diamond eye (who was the one who brought the shipment). Karai then fires at the turtles, knocking them off the container. Leo makes it to the box of missile launchers, but is confronted by Karai. She tells him that she feels betrayed and that he is just as short-sighted and obsessed as The Shredder. She then reveals to Leo that The Shredder is her father (apparently). Leo is shocked by this news. Karai says that the deal is off and attacks Leo. After a short fight the ship returns and Karai hides from it. When she emerges, she finds that Leo has already taken a missile launcher and gone after the ship. Meanwhile, the other three turtles are fighting against The Shredder, but are miserably losing (much like the prior time). Meanwhile, Leo takes aim and fires a missile at the ship. The missile hits its target and the ship crashes into the wharf, knocking Shredder into the ocean. Karai dives in after him, while the turtles retreat. Karai helps The Shredder out of the water. He thanks her, and tells her that he has found a pet for her and holds up a Kraang, which he has captured.
In Karai's Vendetta, Shredder's interrogation of the captive Kraang proves futile, as it does nothing but senseless squealing. Karai suggests putting the Kraang into the limbless exo-suit they possess. Upon hearing it speaking relatively sensible english, the Kraang stated that they hunt the turtles because the latter protect April O'Neil, who is crucial to their plans. Thus, Shredder dispatches Karai to capture April to draw the turtles out. She meets April under the alias "Harmony". She then reveals her identity when trying to feed April turtle soup. April forces Karai to pursue her on foot, but she traps herself in an alley. She pulls out her weapon and Karai compliments on it before disarming her. April tries attacking her directly, but Karai dodges her attacks and starts attacking her, easily overpowering her. She knocks her into the street and demands to know why she's so important as she continues attacking her. April is able to defend herself and provide her own questions. However, just when Karai has her pinned, she mentions losing her mother, causing Karai to hesitate which distracts her long enough for April to throw her down the subway stairs and escape.
In Showdown, Part 1, Karai leads a squad of foot soldiers into the sewers, where they abduct April after she is led away from the Turtles' lair by her brainwashed father, Kirby O'Neil. she then helps lead the foot to the surface where they hand April over to the Kraang.
Later in Showdown, Part 2, Karai intervenes in Shredder and Splinter's battle just as Splinter is about to kill her adopted father. Prior to this, Shredder had revealed to Splinter that after their last battle, fifteen years ago, he had taken Splinter's infant daughter, Miwa, and raised her as his own. Splinter recognizes Karai as Miwa during their brief confrontation, and when Shredder informs her that the rat is Hamato Yoshi, Karai accuses Splinter of murdering her mother, another lie told to her by the Shredder. She attacks Splinter, but her true father refuses to engage her in combat, and leaves.
In The Mutation Situation [which also marks her first non-speaking role in a episode and the series], she walks up to the shredder's throne while he puts his helmet on. She then sets up a projection screen that was recently provided by the Kraang. The Kraang then inform them that their mutagen shipment is ready and is on it's way to them [as they plan to use it to build a army of mutants to destroy splinter and the turtles]. They then inform them that they have a secret weapon that will combat any interferences; a large foot of some kind of ape creature then appears on the screen. After a while, the shredder asks the Kraang where is shipment is. The Kraang then informs him that the turtles have either destroyed or sent their ship off-course to which they state that they will somehow make amends. The Shredder then tells Karai that the Kraang have become useless and that he will clearly have to expand his army on his own.
In Follow the Leader, Karai is set upon by robotic Foot ninja , which were designed by the Kraang to adapt to their opponent's moves. When she was at the robots' mercy, Shredder intervenes. Karai asks if he was going to let the Foot Bots kill, to which he doesn't answer. Shredder then says he's leaving for Japan on business and warned her not to make any moves against the Turtles. But she disobeys and captures Leo, taking him to Bradford's dojo. When his brothers rescue him and escape, Karai catches up with Leo and nearly pushes him off of a building. However, Leo avoids falling by sticking his katana into the ledge, and he jumps behind Karai, catching her unaware. She falls to the ground, where Leo holds a sword to her head and tells her that Shredder is lying to her and that Splinter did not kill her mother, while also ordering her to stay away from his brothers and keep the feud between her and him. As he leaves, he gives one last plea for Karai to believe him about Splinter.
In Mikey Gets Shellacne, Karai dispatches Dogpound and Fishface to find Baxter Stockman so he can maintain her Foot Bots. She later finds her two subordinates, Dogpound mutated into Rahzar, in Baxter's old lab and tells the good doctor that he works for her and the Shredder.
In Target: April O'Neil, Shredder is very unhappy that Karai disobeyed him and sought out the Turtles. Karai blamed her failure on the Foot Bots but insists that the Kraang are improving them. However, Shredder orders to avoid any deals with the Kraang until his return. Again, Karai disobeys and goes to the Kraang, who are building a robotic replica of Bradford's old human form. She then decides on a test run on April. Though the Kraang become startled, they permit the test. Karai eventually confronts April and Don with a squad of Foot Bots. While her robots distracted Donnie, Karai engaged April, bragging that her years of training make her superior, only to be struck in the head by April's tessen. Despite this, she is able to incapacitate April, only for Donnie to come to her defense and knock her down instead. Just then, Bradford arrives and seizes April, it disobeys Karai's orders to kill her as it obeys its Kraang programming to kidnap her for the Kraang. Karai stopped it from taking off with her rival, causing the robot to turn on her. When the other Turtles arrive on the scene, Leo assists April against Karai, forcing her to escape via smoke bomb.
In The Manhattan Project, Part 1, Leonardo tells her that Splinter is her real father, but she does not believe him. She is then stripped of her rank in the Foot Clan by the Shredder who returns from Japan with his new recruit Tiger Claw [who gets questioned and remarks from her about his missing tail] and is now his new second-in-command. He then tells Karai to respect Tiger Claw and follow his orders to which she [now upset] complies to. She then assists Tiger Claw in capturing Splinter and bringing him to Shredder by using the Turtles as bait.
In The Manhattan Project, Part 2, after the defeat of Tiger Claw, Raph then wonders where Karai is now while April still cannot believe that she is Splinter's very daughter. Splinter stated that one day Karai may indeed accept the truth, but that is her decision to make and hers alone. Unbeknownst to all of them, Karai is secretly hiding behind another billboard not too far away from them, hearing everything that they said. Judging by her several facial expressions) not only does she find herself in a difficult dilemma, but finally seems to start questioning herself.
In The Wrath of Tiger Claw, Karai was looking at a photo of her mother when The Shredder asked her what was bothering her. She then told him she wanted the truth about her mother; Shredder then told her that Hamato Yoshi killed her. All is interrupted when Tiger Claw returns; Karai questions how he possibly could've survived, Tiger Claw explains how he escaped and all the dimensions and battles he's been through and how he wants revenge on everyone who made him go through it. Shredder then tells him that he will grant his wish and orders Karai to go with him and destroy the turtles and Splinter. While running through the rooftops and bantering she questions Tiger Claw on what his plan is. Tiger Claw then tells her that she is with him because she knows where the turtles hang out and who their friends are. They head off to Murakami's restaurant where they question him for information. Karai sees how scared he is and states "there's no honor in this" and leaves while Tiger Claw trashes the place and gains information on the turtle's friends. They then go to the movie theater and find Casey, April and Irma there; April senses them and then they split up to separate them. Karai catches up with April and as April prepares for a fight, Karai tells her she just wants to talk. Karai tells her about how the Shredder lied to her and that now she believes Splinter is her father. Donatello and Leonardo arrive and she tells them the same. Leo then decides to take her to the lair, and when they do, Raph is there and states how he doesn't want her there. During the argument, Karai activates a tracking device for Tiger Claw to follow. Splinter enters the room and stops the argument and then sees Karai, telling her to come with him as he has something to show her. He then shows her the pictures of himself, Tang Shen, and baby Miwa all together, and then she finally realizes the truth and tells them she tricked them into taking her into the lair and that Tiger Claw is coming. She then has a plan to lure Tiger Claw away from the lair, and then escapes the lair with the turtles. Still in the sewers Karai doesn't know where to go, but Michelangelo does. They go to a butcher shop where the turtles take on Tiger Claw. However, he proves too strong for them and then offers Karai the chance to finish Leo. She instead attacks him but is unfortunately knocked out by him and taken hostage. Tiger Claw threatens to kill her if the turtles didn't let him go, so they let him go and he gets away with Karai. Later at Shredder's hideout Karai demands the truth from him and Shredder finally admits that Splinter is her true father. He then has her locked up.
In The Legend of the Kuro Kabuto, she is seen in her cell trying to escape by clawing at the door using a miniature weapon. Suddenly the Shredder enters and comes to the opposite side of the door. He then tries to explain why she is with him and that it would have been wrong for her to have been raised by scum like Splinter as well as the fact that everything he did was for them, the Foot and their honor. He then states that one day, he hopes that she will comprehend him for all of this. After he leaves, she continues to claw at the cell door hoping to escape very soon.
In Vengeance is Mine, Fishface is delivering a bowl of food to Karai, who is still in the Dungeon. Karai laments that she hates the food she's being served, but Fishface commands her to consume whatever he decides to bring. Karai quickly corrects that it was Tiger Claw who asked him to bring the food. Fishface tells her to watch her tongue and then departs. However, after he does so, it is revealed that Karai has finished dismantling one of the cell bars, so she is able to separate it from the cell door and use it to bust open the door. Karai then runs to the Dungeon exit and easily picks the lock, only to find Tiger Claw blocking her path forward. Karai attempts to attack him with the cell bar, but Tiger Claw merely grabs it and bends it until it is useless. Karai nearly succeeds in striking her foe, but Tiger Claw pins her down instead. The Shredder then appears and orders Tiger Claw to spare Karai. Tiger Claw agrees and, later, Karai awakens with chains around both of her arms, while Shredder is standing behind her. Shredder takes off the lower part of his mask and asks why Karai has persisted in trying to hurt him. Karai refuses to speak, causing Shredder to ask why 'his daughter' is not responding. Karai harshly screams that she is not Shredder's daughter. After her daring rescue by the Turtles, Leo asks Karai if she is willing to stay with them for quite a while. With Shredder going after them all, Karai says that she has no other choice and confesses that their lair is pretty nice. When Splinter arrives and sees her, Karai then goes over and hugs him, which causes Splinter to believe that some things might indeed be worth the risk. After a training session between the turtles, she glances at the picture of herself as an infant and then asks Splinter about the details of his and Shredder's rivalry. Splinter explains that their rivalry was even deeper than what occurred with Karai's mother. He tells her that the Hamato Clan and the Foot Clan were battling for centuries upon centuries. Oroku Saki was just a young child during the Hamato Clan's final attack, so splinter's father decided to give Saki shelter, and Oroku soon met Hamato Yoshi (Splinter). After that, the two children grew up alongside each other as brothers, and they rivaled one another with their impressive Ninjitsu skills. However, this rivalry only grew bitter when the two of them met Tang Shen for the first time. Not long after this, however, Saki learned about the clan that he truly belonged to (the Foot Clan) and was enraged at Splinter for not telling him. Because of this, he invaded Splinter's household and tried to kill him, but accidentally killed the beautiful Tang Shen instead. He blamed Splinter for everything, so he burned their home down and took Miwa away and rejoined the Foot Clan. Karai then asks her father why he has never sought out revenge, only for Splinter to explain that revenge is the thing that will always lead to more pain - something that the Shredder does not realize. He then says that being reunited with Karai is far better than anything. He then pours his daughter a glass of tea to drink. Soon, the four brothers are preparing to go to bed, and Karai appears to be asleep already. However, Karai then opens one of her eyes, revealing that she was simply pretending to sleep, just so that she could exit the lair. Leo waits for her by the subway tracks and informs her of the danger that would come if she was to face her actual enemies, but he believes they should face and defeat the Shredder, as he will never stop hunting them. Leo then begs Karai to come along with her, and after Karai walks towards him and puts her hand on his shoulder, she mumbles that she's sorry and then throws a ball of blinding powder in his face. She then departs down the subway tunnel, claiming that 'this will end tonight'.Breaking back into Shredder's headquarters, Karai sets her sights on destroying her former 'father', but Shredder has been expecting her return and has a trap well prepared. At Baxter Stockman's lab, Stockman finishes mixing some DNA for a new batch of mutation, only to drop some unknown solution into it, when the Shredder arrives with the foot and Karai, explaining that she would be used as bait in order to capture the turtles and mutate them into mindless snakes to use against Splinter. When Splinter and the turtles attack, Leo manages to reach Karai, only for Shredder to swipe at him, missing him and cutting the chain, watching helplessly as Karai falls into the mutagen. Karai is mutated into a three-headed white snake and wraps herself around Splinter, thinking him to be food, but is reminded that he is her father, which causes her to slither away, and they all escape before the building blows. At the end of the episode, it is revealed that she has the ability to transform into a slightly serpentine version of her human form, which is no doubt due to the unknown substance that Stockman accidentally dropped in the DNA before adding it to the mutation.
Karai makes three brief cameos in the season 2 finale, The Invasion. In the episode's beginning, Shredder has flashbacks of key moments in her life, including her training and mutation. Then, she appears shortly as Casey and Raphael are looking for her. Then, at the very end of the second part, she saves Splinter from drowning, gently nuzzling him awake before slipping away into the water.
In Serpent Hunt, the turtles search for her while she is being hunted by Ivan Steranko and Anton Zeck as well as Fishface and Rahzar who try to capture her on Shredder's orders. The turtles manage to track her down to an abandoned factory where they get attacked by the Kraang who she easily takes out. They then try to talk to her, where Donnie realizes she is becoming more snake-like. She then transforms into a human, where it's revealed her human form looks more pale and scaly then it did after she got mutated, and informs them that it's to dangerous to go with them. Fishface and Rahzar show up and manage to capture her by stunning her with a taser. Ivan and Anton then capture her and attempt to make a deal with the Shredder by handing her over to him so he can help them escape the city that the Kraang have taken over and constantly patrol everywhere. The turtles then show up and free her while they fight the shredder. She then gives them a clue; pointing to the East and the word "comet" before she escapes by jumping into the water at the docks.
In The Pig and the Rhino. The Turtles, Casey, and April discover three potential places that Karai could be hiding and split up to find her with retro mutagen in an attempt to change her back. Leonardo and Michelangelo discover she's been at Coney Island and her hint regards the Comet Roller Coaster. Karai evades them in the Haunted House attraction but they corner her outside, where she almost attacks Mikey but is stopped by Leonardo. He asks her if she can change forms but it appears that she can't. She runs away once the now mutated Steranko and Zeck show up (who Mikey calls Bebop and Rocksteady). When Bebop and Rocksteady fight over the retro mutagen she appears and spits acid in Rocksteady's face, causing him to drop the retro mutagen and crush it as she escapes into the haunted house with Bebop following her. This distraction allowed Leo to free his brothers, April, and Casey. After the turtles defeat Bebop and Rocksteady, Karai comes out and Leonardo sprays retro mutagen on her, but to their disappointment it has no effect, as Donatello says that Karai is a special kind of mutant. Leonardo offers to bring Karai home, but she thinks it's too dangerous as her mind is still deteriorating. As it turns out, she only brought the turtles to the location so she can say good bye to all of them as she once again escapes into the water. Later, in the streets, she tries hunting a nearby rat, but it was a trap set up by Bebop and Rocksteady, who take her to Shredder's lair. Shredder swears that he will cure her and they will have their revenge on the Turtles, as Karai angrily hisses at him.
In Casey Jones VS. The Underworld, Karai is seen imprisoned behind a glass wall in Shredder's Lair, banging on the wall for escape, as Shredder once again promises they will reverse her mutation.
In The Noxious Avenger, she is briefly seen in her cage in Stockman-Fly's lab.
In Clash of the Mutanimals, she is seen imprisoned in Shredder's lair, where she overhears Shredder's plans to use the mind control serum on her.
In The Deadly Venom, Stockman-Fly successfully restores her human form and infected her brain with a Mind Controlling Worm. Shredder then orders her to attack Rocksteady who she defeats easily. Shredder then orders to hunt and destroy the turtles and their allies. She first sends a bunch of venomous snakes to bite April and then she got the drop on Casey. He gave her a good fight but by using both her ninja skills and her new control over her mutant powers she over powered him and gave him a poisonous kiss. When Mikey and Raph came to save him Karai's snake came out of Casey's clothes and bit them. She then used all four of them as bait for Leo and Donnie and she placed some of her venom in the water they swam in. With Leo poisoned she quickly got the upper hand but by using a healing technique Splinter recently taught him, Leo beats her venom and defeated her, but when he turned his back for a minute she was gone.
In Tale of the Yokai, she is seen as in infant with her mother Tang Shen. Her mom leaves her unattended to go after Splinter and Shredder. After her mother's unfortunate death, she is stolen by the Shredder who renames her Karai.
In Attack of the Mega Shredder!, she is seen briefly being attached to some kind of contraption as she's forced to endure multiple worm injections due to the fact that one single mind-worm is not enough to keep her under the Shredder's control (most likely from her fight with Leo involving the healing hand technique in The Deadly Venom). The Shredder apologizes to her and promises her that they will soon have their revenge on Splinter and the Turtles. Bebop and Rocksteady are then assigned by the Shredder to watch over her as well as secure the base from the turtles.
In The Fourfold Trap, she sets up a trap for the turtles with Shredder's other henchmen to lure Splinter to her. She lures Donnie first by having Stockman hack into his T-Phone and making him think April is calling him. After that, she captures Mikey by luring him to Murakami's and having him eat pizza gyozos spiked with a chemical to knock him out. Finally, she lures Leo, Raph and April when she fakes a phone call from Mikey. When they arrive, they are quickly overwhelmed by Karai and the other mutant henchmen. Karai has the turtles placed in separate rooms each filled with a different trap, while April is chained near Karai. April then has no choice but to call Splinter and warn him, where Karai takes her phone and finally talks to Splinter, who is surprised to hear his daughter after so long. Splinter arrives where the Turtles are kept, and he defeats each and every one of Shredder's henchmen until only Karai is left. He tries to reach his daughter and pleads for her to stop, even calling her Miwa, but she doesn't listen and attacks him. During the fight, he tells her that he loved her mother very much, but this only infuriates her. Splinter dodges all of Karai's attacks and knocks her weapon out of her hand. He then says that he won't fight her. She reverts to her mutant form and says that he doesn't have a choice before lunging at him. Splinter narrowly avoids getting hurt by her as he tries to dodge her attacks, until she dives into the water around the command center. Splinter then takes Leo's suggestion about the healing mantra and goes through the motions as Karai circles him in the water. Just as she tries to attack him, he finishes the hand motions and hits her several times in crucial areas with the mantra. He then tells her he loves her before pressing two fingers into her head. She spits venom in his eyes, and wraps around him. Just as she is about to finish him, she screeches in pain as the brain worm that's controlling her weakens, causing her to let go of him. She thrashes in pain and throws herself off the platform until Splinter grabs her by her wrist. Unfortunately, her wrist slips out of his hand and she falls into the water as it drains into the sewer, taking her with it, much to Splinter's sadness. At the end, she lands in a sewer pipe and changes back to her human form. The healing mantra that Splinter performed on her is shown to have worked as she pukes the brain worm out of her mouth, thus restoring her free will.
In City at War, after being freed from the brain worm, Karai calls her old friend, Shinigami, from Japan to aid her in taking down Shredder's criminal empire. When Shinigami returns to Karai at Shredder's old headquarters with a tanto carrying the Hamato Clan insignia, they soon are confronted by April and the Turtles, as the tanto belonged to April. Karai explains that she's no longer their enemy now that she's free of the brain worm, and explains her plans to rebuild the Foot before Shredder's corruption, take down his criminal empire, then Shredder himself, once and for all. The Turtles offer their support, but Karai believes she needs to do this herself. However, she does allow April to face Shinigami again for getting her tanto back. Though Shinigami easily beats April, Karai agrees to return the tanto, before the Turtles and April then take their leave. Later, Karai and Shinigami arrive at a martial arts store that Karai knows is a front for Shredder as he keeps a cache of weapons in the back. They are soon attacked by Tiger Claw, Fishface, and Rahzar, and before surrendering after Tiger Claw takes Shinigami hostage, Karai sends a text message for help to the Turtles. After being subdued, Karai frees herself, but is soon overpowered by Tiger Claw, who prepares to kill her before the Turtles and April arrive to help after getting Karai's text message. As Karai and Leo fight Tiger Claw, at one point, Karai allows her mutant self to surface as she turns her arms into their mutant form to attack Tiger Claw with, but he is still able to overpower her before April incapacitates him with The Dragon's Tail, allowing Karai and Shinigami to escape with the Turtles and April, but not without leaving behind enough explosives to wipe out the weapons cache for Karai. Back at the Turtles' lair, Karai speaks to Splinter about what she's doing, and though he wants her to join the Turtles and work together with them, Karai explains that she's grown up now and needs to deal with Shredder in her own way. Splinter voices how proud she is of her as she departs with Shinigami to continue her plans with rebuilding the Foot and wiping out Shredder's empire, not realizing that she may have started a war with Shredder that's she's not going to win.
In Broken Foot, Karai and Shinigami are aided by Leo behind Splinter's back as they continue to systematically take down Shredder's criminal empire, taking down Hun and his Purple Dragons before burning a temple full of Shredder's laundered money, then attacking Auman Chemicals, encountering resistance in the form of Foot-bots, Tiger Claw, Bebop, and Rocksteady, but managing to plant their explosives and damage the facility, aided by fresh Foot Ninja from Japan. However, Donnie was injured trying to save Mikey and Raph from the explosion, and as a result, Karai and Shini are forced to flee from Tiger Claw before he goes after the Turtles with Bebop and Rocksteady. When Leo arrives at Shredder's old lair with Mikey and Raph, Karai reveals her next target to be the Foot-bot manufacturing facility at Auman Chemicals. Destroying it would cripple Shredder's army beyond repair, but having witnessed what Karai's revenge did to Donnie, Leo wants nothing to do with it, leaving Karai to blind him and his brothers, while Shini uses her magic tricks to further disorient them so Karai can take Shini and the Foot Ninja to still take down the factory. However, their plan falls apart due to Tiger Claw, Bebop, and Rocksteady anticipating their arrival and having the factory crank out Elite Footbots, which manage to overpower Karai, Shini, and the Foot Ninja, capturing them. However, Leo, Raph, and Mikey arrive to save Karai and the others, but thanks to Raph fiddling with the control panel, the Turtles, Shini, and the Foot Ninja are sorely outnumbered by Elite Foot-bots, until Karai plants an explosive on the large cistern at the top of the factory and detonates it manually, burning the side of her face, but causing the cistern to plunge into the molten slag below, splashing it on the Elite Foot-bots and destroying all of them along with the factory. Leo retrieves Karai, and together with Mikey, Raph, the Foot Ninja, and Shinigami, they escape as the NYPD flood to the factory, now a raging inferno, regrouping in an alley where Karai uses her mutant abilities to heal her burn wounds similar to a snake shedding it's skin, much to the Turtles' amazement before they return to their sewer lair. Once there, while the Turtles are overjoyed to see Donnie fully healed thanks to Splinter's healing mantras, Karai apologizes to Splinter for having allowed her revenge to bring harm to others. She then decides that taking down Shredder's criminal empire is no longer her priority. As of now, she's going to go after the Shredder himself, turning to leave and drawing her tanto blade as she does.
In The Insecta Trifecta, Karai has ordered to her Ninjas to look for Shredder, as they report no sights of him, she starts to look impatient and upset and demands her Ninjas to leave her. As they leave, Karai notes on Stockman's Antrax around the lair and Stockman has arrived. She relates of all Shredder's mutants he would send to take her down, he just sends a useless bug, much to Baxter's frustration, but even she could turn to her mutant form she gets stuck in spider web until the Turtles and April arrive, but thanks to Raphael's hallucinations, she gets captured anyway with Leo and April. She is seen in a spider web with Leo, April and Casey (who was captured as well before her) in a high-rise construction and worries if Stockman and his minions are going to eat them. She is rescued by Mikey, Donnie and Raph and along with April she fights the bugs and gets Stockman out of the controls of the crane.
In The Super Shredder, Karai is at her base when a blackout occurs. When Shinigami reports she has no idea how it happened, Karai suggests doubling the guards outside, only for Tiger Claw and Rahzar to enter. Karai is ready to fight them, when they reveal Shredder is with them, entering to reveal he's become what Karai says he hated the most: A mutant. Shredder manages to take out Shinigami, their Foot Ninja, and Karai, in her mutant form, before threatening to hunt down Shinigami if Karai does not surrender to him. Left with no choice, Karai surrenders, and watches as when the Turtles and April arrive in the Shellraiser to save her, Shredder easily overpowers the Shellraiser and sets it ablaze, much to Karai's horror.
Afterwards, Karai is taken to be held hostage in the area where Shredder and Splinter had their last battle that Shredder won. When Splinter arrives to save her, he is confronted by Shredder, and soon forced to retreat when he realizes he's no match for Shredder in his mutated state. As Splinter lures Shredder away, Karai frees herself and regroups with the Turtles and April, only to be stopped from pursuing Shredder and Splinter by Elite Footbots. By the time they reach Splinter and Shredder in the under-city where Splinter fought the Rat King, they are unable to help as more Elite Footbots block them from reaching Splinter, who manages to collapse the broken bridge segment he and Shredder are on, before dragging Shredder with him to their presumed deaths. As the Elite Footbots begin to rain arrows on them, Karai, April, and the Turtles are forced to retreat and regroup, knowing that Splinter might still be alive if he survived the fall. Before they can consider it further, the doors they were hiding behind are blown open, and they find themselves confronted by Bebop, Rocksteady, and at least a half-dozen Elite Footbots...
In Darkest Plight, Karai encourages the team to take down Bebop, Rocksteady and the Elite FootBots for Splinter, but they retreat due to the number of Elite FootBots. April called Casey to help them search for Master Splinter. As Donnie, Mikey, Raph and Casey search in the abyss of the under-city, Karai, Leo and April are going to watch for Shredder and his goons. April senses Shredder and Tiger Claw's presence and Shredder orders his loyal bounty hunter to destroy April, bring Karai to him alive, and also Leonardo so Shredder could destroy him personally.
Tiger Claw follows the trio to a roof, knocking Leo off and almost killing April but Karai defends April and defeats him using her serpent form's tail to throw him into some power lines to electrocute him, knocking him out for a while. She and April arrive to help Leo against Shredder. As Shredder is hit by a truck, he lifts it and throws it right to Karai, but she's saved by April using telekinesis. As Shredder runs to Leo and prepares to end him, Karai begs him to do not do this as he could do something good for once in his life than wasting it with revenge. Shredder gets touched by this, but Karai was just using this to give Leo time to escape. Karai then screams at him, saying he was never her father, and punches right in his mutated heart, which causes him to spill mutagen from his mouth and limp away, severely weakened. Karai prepares to finally kill him, but Tiger Claw arrived to rescue him. April asks her to forget Shredder as Leo needs medical attention. Karai agrees, saying next time they'll make Shredder pay for what he did, and she helps April take Leo to the lair.
In Requiem, with the old lair no longer safe, Karai and Shinigami take up residence with the Mighty Mutanimals in the Bronx, but their relief at being safe is short-lived as Super Shredder lays siege to the hideout and sets it on fire. As Karai faces him, Super Shredder taunts her at how she'll die just like her mother Tang Shen. Enraged by that, Karai charges Super Shredder, but thanks to his mutation being stabilized and strengthened, Karai's tanto blade shatters upon trying to stab his mutated heart, and Karai is knocked off the catwalk and buried under debris, left to die in the inferno. Leonardo and Splinter arrive and manage to pull Miwa out, but once outside, she's not responding. Leo performs CPR on her and manages to revive her, much to Shinigami's relief and gratitude. As the NYPD and FDNY are heard approaching, Shinigami stays behind with Karai so she can be taken to the hospital by the paramedics to be treated for her injuries.
In Owari, Karai is in the hospital, having suffered numerous bruises, cuts, abrasions, and a broken arm, but is expected to make a full recovery. When the Turtles arrive to tell her about her father's death, hoping to avenge him, Karai gives them the location of Super Shredder's hideout so they can end things once and for all. Once Super Shredder has been eliminated, Karai joins the Turtles, April, and Casey on a rooftop overlooking the city, knowing that with Shredder gone, there will be a major power struggle to fill the gap, but they will be ready for it, knowing Splinter is watching over them from the afterlife with pride.
In The Forgotten Swordsman, Karai and Shinigami track the Foot Soldiers to a warehouse. Karai also reunites with one of her old teachers, Hattori Tatsu, but is not able to beat him even she reverts to her serpent form and she escapes thanks to Shinigami and her bat distractions. She and Shinigami arrive to the Turtles' lair and reveal someone is after the Kuro Kabuto and Mikey and Raph arrive to reveal the Kabuto'll be used to bring Shredder back from the dead. Shinigami explains that if they keep the helmet out of Tatsu's hands the ninjas will side with Karai. They're only chance for survival is to take him down. They create a plan to get the Kabuto. Karai, Leo, Shinigami and Mikey'll turn off the lights and fight Tatsu while the others stay alert to the Foot Soldiers. While Tatsu beats them Karai manages to take off Tatsu's Oni mask revealing, to Leo's shock, he's totally blind. However despite being blind he has a good sense of hearing and can block everyone's attacks. Tatsu takes Shini and Mikey out of the battle and Karai once more tries to beat him using her mutant form but gets beaten again. Casey throws his explosive pucks at Tatsu to prevent him from killing Karai. During the battle Leo gets an idea. he throws Casey's pucks at Tatsu's front to disorient him but he manages to block Karai's sword attack but didn't know Leo jumped behind him and disabled his hearing with a nerve move. Karai sees this chance to defeat her old teacher with her mutant form and she beats him. Karai changes back to her human form, informs the soldiers they're being used by Tatsu just like Shredder did and the Foot Clan deserves a noble destiny before asking Tatsu to go back to Japan. Tiger Claw, Rahzar and Kavaxas arrive and the latter drains Tatsu's soul leaving him dead and under Tiger Claw's orders tries to kill the Turtles but April creates a shield with her psychic powers leaving Tiger Claw, Rahzar and Kavaxas escape with the Kabuto. Casey and Shinigami are taken to hospital and Karai apologizes for going after Tatsu but the team promise each other to stop Kavaxas once and for all.
In Heart of Evil, Karai assists the turtles to find the next phase of Tiger Claw's plan to revive Shredder. She and April are on a motorcycle chasing Bebop however he then blasts them but April saves herself and Karai from falling. Karai, with the turtles watch over Don Vizioso's hotel and is waiting for Kavaxas and Tiger Claw to show up. Karai with her mutant form pins down Kavaxas to allow April get the Seal of the Ancients. Karai with the turtles are then defeated again by Kavaxas.
In End Times, Karai and Leatherhead are called by Michaelangelo to help them defeat Undead Shredder and Kavaxas once and for all. She then pushes the Undead Shredder back to the Netherworld. Karai and Leonardo watch as Kavaxas is sucked back to the Netherworld along with Shredder pushing him to the portal.
When Karai makes her first appearance in New Girl in Town, she is portrayed as quite a rebellious teenager and expert Martial Artist, who stirs up trouble at times.
Karai is typically portrayed to be an evil character, but one that always has conflicted emotions. She reveals in the freedom that The Foot Clan gives her, and she often takes advantage of it at every turn, choosing to toy with/fight the Turtles. However, she still does operate on a bit more complex code than her "father" or clan does, and, at one point, she seemed to have a bit of a greater concern over the community around them (and the Turtles) than her father did. For example, she once tried to persuade her father to look into the Kraang and possibly become allies with them to use their advanced tech (The Shredder didn't listen to her at first, but then did after quite a long while). There are also several times that she has actually tried to aid the Turtles in their constant battles against the Kraang, but, at the same time, she also has tried to kill the heroes by leaving him to deal with a violent aberration mutant that she carelessly, yet purposely created - and she has tried to kill them many a time on her own as well. She was, at first, seemingly rather intolerant of the grudge her father has for both Hamato Yoshi and the Turtles, but she later turned out to be nearly as vindictive as her adoptive "father" is, especially after she comes to face to face with Splinter (in "Showdown, Part 2", when she finds him engaging in a mortal duel with the Shredder) and this ultimately brings out the true emotions that she had concealed for years upon years. This also ended up causing her to get enraged when she came across Splinter battling (and slashing one of his shoulders). Also, because of this, she often chooses to vent her anger and jealousy on those who are undeserving (such as April or Leonardo). Her rebellion has now made her dangerously unpredictable with all four of the Turtles; however since she has found out that Splinter is her true father, her behavior and view of them all has changed as she assisted Tiger Claw in finding them so she could talk to them (while Tiger Claw wanted to kill them as payback) and then assisting them in fighting Tiger Claw in the meat locker. she has also defected from the Foot Clan and has now made it her mission to kill the Shredder for his deception.
Karai is quite intrepid, and she clearly has enough bravery to disobey her 'adoptive' father (such as when he leaves on a journey for Japan and orders her to temporarily take his place). However, she is equally afraid of him sometimes (especially when he threatens her). However, she still cares for him as her "makeshift father", and would be more than willing to protect him if the situation calls. This changes after she finds out that Hamato Yoshi is her true father, and not Shredder. She has now made peace with Splinter and the turtles and has made it her mission to kill Shredder in revenge for her mother's death and for lying to her for her whole life.
As a Human
As a human she is shown to be slightly taller than Leo and April. Karai has black hair that is blonde in the back with an angled bob and long ear-tails. She wears several black earrings and red eyeliner on the top of her eyelids. She has amber eyes. Karai wears silver armor, black material worn under her armor, traditional Japanese shoes, and a purple belt with a design on it like the Shredder's. She does have a civilian outfit as well with a punk design, consisting of worn jeans, biker boots and a leather biker jacket with metal studs.
As a Mutant
As a mutant she is a two armed white and purple serpent with green eyes, snake heads instead of hands, a mouth in the back of her head and with her armor melded into her skin.
She appears mostly human, but with Snake eyes, fangs, tongue and her skin is paler with certain parts scaly
Powers and Abilities
As a human, her skills as a kunoichi are so great that she can take on Leonardo one-on-one or all four turtles at once. As seen in Enemy of My Enemy, her primary weapon choice is a wakizashi (a short yet sharp Japanese blade).
As a mutant serpent she has incredibly fast reflexes, an amazingly strong tail that can be used for whipping, constricting and crushing, and she can spit blinding venom.
She is also shown to be able to morph between her human and mutant form. As the mutagen Shredder set up was designed to turn the victim into a mindless snake, Karai does struggle to keep her human mind in tact compared to other mutants. Donatello notes that Karai is a special type of mutant, as normal retro mutagen doesn't seem to turn her back to normal.
In "Serpent Hunt" Karai reveals to have a mouth on the back of her serpent head which she can hide for surprise attacks.
In ''The Deadly Venom'' she is seen with her mind completely restored (albeit under Shredder's control) and has better control of her morphing ability, she can also switch between human and serpent, like having a human body with snake arms. She also seems to have gained telepathic control over snakes and her venomous bite (or kiss) can cause numbness, weakness, paralysis, then black out and sometimes hallucinogens. If not treated soon, the venom can prove deadly.
In The Fourfold Trap, she is shown to be able to revert to her completely human form with no serpentine characteristics.
As shown in Broken Foot, Karai now also has the ability to heal damage to her skin (such as severe burns) simply by shedding it when turning into half-snake form.
"Not bad - You might actually be a challenge. (knocks Leonardo to the ground in the blink of an eye) "Guess not. My name is Karai. See you around."
"You always talk to yourself?"
"I'll listen, when you beg for your life! Let's see how well you do against someone who's better than you."
"I understand... Father."
"Stop being responsible, Leo. Stop waiting for others to give you the life that you want. Go out and take it."
-New Girl in Town
"They're fighting robots?"
" Oh you were there? I didn't notice. I did see a bunch of robots though, what's their deal?"
"I like your brother, Leo. He's almost as entertaining as you."
"(Laughs) You're adorable! Stupid but adorable."
"No. You're trapped. What happens when I do this? Well now I gotta."
"I know! That's messed up right!?"
. -The Alien Agenda
"Yeah, because if Shredder finds out you have an ice cream lamp, it is over!"
"You guys need my help. You really think you can shoot down an alien warship with garbage? My point is to take down a ship like that, you need a real weapon. What if I get you a shoulder fire missile launcher? Shredder won't know about it. He's buying a big ship full of weapons down on the docks tomorrow night. All we need to do is sneak in and help ourselves. And why would I trap you? You're the only ones who know what The Kraang are up to."
Later...(to Leo, who attempts to assassinate her father) "You're just as short-sighted and obsessed as Shredder! You want a feud? You've got one!"
"I'm not really that good about saying thank you...That was it."
- Enemy of My Enemy
"So this April O'Neil is at the center of everything?"
"What's your name? ... My name's Harmony."
"Now you try mine... Supon nabe... Turtle soup."
"A Tessen. Beautiful, unassuming... But very powerful. In the right hands."
"What makes you so special? You're the center of an alien conspiracy, protected by mutants, and trained by a great ninja master... Why?"
"What...? You lost your mother?"
- Karai's Vendetta
"Hey there princess. Miss me?"
"You've done well. Now take the message to Splinter."
"I know! Pretty cool right?"
"NO! Father! My name is Karai! Father told me what you did to my mother. And now I'm going to return the favor. Why won't you fight? COWARD!"
"So the turtles are searching for the missing mutagen canisters. This makes the game so much easier."
"I thought they'd finish me but you wouldn't let them right father?"
"Foot bots! Deshell him!"
"I never got to know my mother because your rodent master took her away from me."
- Follow the Leader
"(to Fishface) Dad put me in charge while he's in Japan, remember? So either learn some respect or I chop off your robo-legs and drop you in the sewer. Got it?
" Rise and shine Stockman. You're working for me now, well me and the Shredder. Let's move!"
-Mikey Gets Shellacne
"Not bad, How long before it's operational?"
" 9 Hours!? I want to test it on someone now! And I've got the perfect target too. April O'Neil."
"Foot bots keep the turtle busy! This is between us girls."
"Your skills are weak April. I've had years of training'"
"Like my new little toy? Robot! Eliminate the girl!"
-Target: April O'Neil
"I have no honour, but that is about to change"
"I didn't come to fight, I came to talk"
"I believe you Leonardo, I believe that Splinter is my true father"
"Father, what have I done?"
"Tiger Claw is tracking me"
"I...I don't know"
-The Wrath of Tiger Claw
"(To Fishface) "Wel, if it isn't the sushi I ordered."
(To Shredder)"I am not your ...Daughter!"
(After escaping)"This isn't over, Tiger Claw."
(First words as a mutant)" ... Father ? "
-Vengeance is Mine
(To Leonardo) "Leo.... Give Shredder a couple of hits from me."
(To Leonardo) "There's nothing to be sorry about, I just wanna thank you for finishing what no one else could."
Family and Allies
Leonardo is the first of the Turtles that Karai meets. While she attacks and fights with him often, she never does him any serious harm and just enjoys sparring with a worthy opponent. Leonardo, in turn, was both confused by and attracted to Karai (as shown in "New Girl In Town"). She is dangerous, but Leo believed that there was some good in her but she betrayed him. She seems to be deceitful and manipulative in The Alien Agenda, using Leo's feelings for her against him, especially in his time of need. In Enemy of My Enemy, she returns, seeking information about the Kraang from the turtles. This time, instead of wanting to fight the turtles, she decides to make a truce with the turtles in order to defeat the Kraang ship. She goes against the Shredder's orders because she knows they'll all die if they don't set aside their differences and take down the ship. At first, the turtles, mainly Leo, are very skeptical of her and decline her request for a truce, but after she leads it away from the Shellraiser, they comply. Because Leo saved her and allowed her to speak to all of Turtles, Karai develops some friendship for him. However, because he and his brothers tried to attack her father, the truce was called off and her trust in him was left now uncertain. Now she's vengeful towards the turtles and is willing to do whatever it takes to take them down. It was revealed in the Season 1 finale that Karai is Splinter's lost daughter (Miwa), who was raised by the Shredder. Leo seems more aggravated with Karai as she wants to hurt him and his loved ones more often, he tells her that her vendetta is with him not his family. In Follow The Leader Splinter told Leo that Karai is his daughter. Near to the end of The Manhattan Project, Part 1, Leo told Karai that Splinter is her true father but she neglects it. In The Wrath of Tiger Claw, Karai was thinking about what Leo said about Splinter being her true father. When Karai finally realized that Splinter is her father, she betrayed Tiger Claw in trying to terminate the Turtles and Splinter, which caused Tiger Claw to take Karai back to Shredder to be locked in a cell. In Vengeance is Mine, Leo and his brothers staged a rescue operation to get Karai from Shredder. It worked well and Karai was reunited with Splinter. When Leo and Michelangelo was training, Michelangelo threw one of his water balloons at Leo, which made Karai giggle. When Karai was planning on taking down Shredder, Leo wanted come along with her. Karai came close to Leo and temporarily blinded him with a smoke egg. Splinter, Leo and his brothers went to rescue Karai again. Leo was about to rescue Karai when all of sudden Shredder broke the chain that was holding Karai's cage, which caused her to fall into the mutagen. When she becomes a mutant, Leo appears to be one of the only people (aside from Splinter) that can help briefly restore Karai's mind by reminding her of who she is.
Raphael, Donatello and Michelangelo
Raphael is the second of the Turtles that Karai meets, and Raph is the first to find out about Leonardo's "friendship" with her. Unlike his brother, Raphael immediately distrusts her. He tries to warn Leo that she is the enemy and not to trust her. Raph came up with the idea of setting a trap for Shredder and (like the rest of his brothers) attempted to assassinate the Shredder. He still does not trust her when she wants to help defeat the Kraang. Donatello does not know too much about her mainly because Leo never mentioned her until after they revealed her in The Worldwide Genome Project headquarters. Based on Donnie’s observations of her, he does not like her because of her need to cause trouble. He is wary of Karai's tactics and does not trust her at all, not even when she offered to help him and his brothers fight the Kraang. Donnie also was a part of the attempted assassination of the Shredder. Michelangelo also did not trust her and was surprised that Leo trusted her. When she wanted to help fight the Kraang, Mikey was wary of her. Mikey also participated in the attempted assassination. They see her as an enemy working for the Foot, but she sees them more as play toys for her amusement. In Showdown, it is revealed that Karai is Splinter's daughter, Miwa, who the Shredder took and raised her as his own daughter after the events of their final battle. When Splinter told the turtles about this, they were all shocked and Mikey questions about Karai being their "sister". The Turtles rescued Karai from The Shredder in Vengeance is Mine. They brought her back to Master Splinter, where he was shocked to see his daughter return. Later, Karai watched the Turtles train and she giggled when Michelangelo threw a water balloon at Leonardo's face. At this point, the Turtles see Karai as a part of their family. When Karai was mutated, the Turtles and Master Splinter were deeply depressed. Michelangelo asked Donatello if he could make a retro mutagen for Karai but Donatello stated "I hope so".
April is the first female human that she has met in the whole series. Based on their brief encounter in "Karai's Vendetta", they seem to have quite a lot in common. They both know how to speak Japanese, they both know how to drive a motorized vehicle, they're both kunoichis (except Karai has better Martial Art skills), they are both the romantic "interests" of one of four Turtles, and both of their biological fathers have been mutated into animals. They seem to become enemies in "Karai's Vendetta" (though Karai does seem to have a regretful expression on her face not very long after she attacks April). It is also suggested that Karai dislikes April somewhat and is jealous of her, due to the fact that she is very special and important to the Kraang and Splinter (a value that Karai doesn't think she has). At the very end of this episode, however, Karai appears to show signs of empathy and feeling slightly sorry for April when the other girl mentions that she lost her mother. If they weren't on different sides, it's likely that the two could be very good friends. However, their current views of each other have change now that Karai has found out and accepted that Splinter is her biological father. Also in The Wrath of Tiger Claw, she chased down April to just talk to her instead of fighting. She then opened up to her about everything that was happening, Splinter possibly being her real father, Shredder lying to her for her whole life and where her loyalties lied, and her possibly betraying the Shredder which surprised April. They are then seen enjoying each other's company as they had a conversation until the turtles arrived. She then told the turtles that she believes Splinter is her biological father. April then tells them that she believes that Karai believes this to be true showing that she now trusts Karai.
Karai is Tang Shen's daughter, along with Master Splinter's. When she was an infant, her mother perished at the hands of Shredder when she intercepted a blow meant for Splinter, and was taken in by him. He then raised Karai as his own child and fed her countless lies about how her mother died and who committed the act. Karai has known this false truth for a big portion of her life, but when Splinter showed up in Shredder's hideout in "Showdown", her true feelings on the situation are exacerbated even more and she now desperately hopes to avenge her own mother's death by killing her true father. Even though she doesn't know what her mother was actually like, she carries a torn-off, dilapidated photo of her mother around with her. It is likely that this was part of a grander, family photo like the one Splinter has in the lair, but the Shredder probably ripped Tang Shen's part off to conceal his own lie.
Karai is none other than Splinter's biological daughter. In the episode "Showdown Part 2", Splinter discovers this after the Shredder reveals to him that he took his daughter, Miwa, away and raised her as his very own child. When Karai soon shows up, he is then able to turn Splinter's own daughter against him by using what he had formerly told her about whom killed her mother, Tang Shen. She then tries to fight Yoshi, but he manages to avoid her attacks and escapes. She then demands to know why he won't fight with her and calls him a coward. He then leaves, heartbroken at what the Shredder has done to his daughter....In "Follow The Leader", she demonstrates how truly spiteful and vengeful she has now become towards him. She hates him to the point where she wanted to kill the Turtles before his very eyes and ruin his life in so many more ways. When she successfully tranquilizes Splinter in "The Manhattan Project, Part 1", she seems to view this as a big victory and she also even appears to draw some sadistic pleasure from doing this. It is very clear that Splinter knows that his daughter is fully alive, active, and working alongside the Shredder, In The Manhattan Project, Part 2, she over hears Splinter talking to the team about him being her biological father and whether if she will figure it out and accept it is her decision. She then has a guilty expression on her face suggesting that she's starting to question herself and everything else. In The Wrath of Tiger Claw, her knowledge of the truth caused all her hatred of him to disappear and after her rescue in Vengeance is Mine she hugged him for the first time. After her mutation into a snake-like creature, her love for him gave herself the strength to fight her new instincts and not devour him. In The Invasion, Part 2, mutant Karai saves Splinter from drowning in the sewer waters and gently tapped on his shoulder to check his vital signs, which shows that she deeply cares about her father.
Shinigami is an old friend of Karai's from Japan and has tried to help her rebuild the Foot Clan in a more honorable image.
Karai's former relationship with her foster father was actually quite complicated. She seems to fear The Shredder at certain times, just like Bradford and Xever do, yet she obeys him, but she doesn't appear to respect him as much. It is possible that she wants him to respect her equally, such as when she mentions The Kraang and shows him the droid she had picked up, attempting to intrigue him somehow. In "Enemy of My Enemy", just a little more insight is given into Karai's relationship with her Shredder. Karai saves him a total of two times in this very episode. She tackles him out of the way to prevent him from getting zapped by an electro-grenade and bravely jumps into the sea to save Shredder from drowning towards the end of the episode.This proves that Karai truly loved Shredder as her father despite constantly disobeying his orders.That all changed when she finds out that Saki is not her true father, she betrays him and he has her locked away in his lair's dungeon, after that event she began to hate him for lying to her for her entire life. In Vengeance is Mine she learned that it was shredder responsible for her mother's death and how he kidnapped her. She wanted revenge on him so much that even after her real father told her that "revenge only leads to more pain”, she rushed to his lair to face him.
Relationship is vastly unknown for the most part, but Karai did seem to stand up for both Bradford and Xever in a way when she told the Shredder that his own men got turned into hideous freaks when she wanted Shredder to try and help her figure out what was going on with the Kraang.
At the moment they first met, they did not like each other. All of the other members of Shredder's forces seem to be rather stunned to see such a menacing looking man beast, while Karai coldly asks why The Shredder has enlisted yet another freak. Right afterward, Tiger Claw tells the Shredder that he is quite disappointed that this is the Foot Clan he told him all about. Karai continues to show no respect by teasing him about losing his tail. She was angered by the fact that Shredder made Tiger Claw his second-in-command instead of her, but was willing to work with him until she finally accepted the fact that Splinter was her real father and betray him and the Shredder.
- The Mutation Situation (cameo)
- Follow the Leader
- Mikey Gets Shellacne
- Target: April O'Neil
- The Manhattan Project
- The Wrath of Tiger Claw
- The Legend of the Kuro Kabuto (cameo)
- Vengeance is Mine
- The Invasion
- Return to New York (2012 TV series episode) (as a picture)
- Serpent Hunt
- The Pig and The Rhino
- Casey Jones VS. The Underworld (Cameo)
- The Noxious Avenger (Cameo)
- Clash of the Mutanimals (Cameo)
- The Deadly Venom
- Tale Of The Yokai (as Baby Miwa)
- Attack of the Mega Shredder! (Cameo)
- The Fourfold Trap
- The Forgotten Swordsman
- Heart of Evil
- End Times
- When Worlds Collide, part 1
- When Worlds Collide, part 2
- The Crypt of Dracula (Cameo)
- Miwa strongly resembles Leonardo's Wife from the Mirage TMNT miniseries Tales of Leonardo: Blind Sight. In this story, Leo experiences a vision of another life where he is a turtle samurai in feudal Japan. He has an unnamed human wife, and together they have a daughter named Yumi. Leo's wife and Miwa have facial structures and hair styles that are very similar. But unlike Miwa, Leo's wife also ties her hair, wears no eyeliner or face paint, and her widow's peak is positioned higher and away from the "villainous widow's peak" style. Overall, Miwa as Karai looks like a more evil version of this character.
- The false name that Karai gave April in Karai's Vendetta, Harmony, can be written in Japanese as "Miwa".
- In "The Wrath of Tiger Claw", Karai finally learns and accepts the truth of Master Splinter being her real father.
- Karai's ability to change her current mutation, back to her "normal" self again, is an act very similar to of the snake lady from the movie Hisss.
- Karai's mutant form with the snake heads for hands bears a slight resemblance to previous Ninja Turtles' villain Scale Tail.
- Serpent Karai has a mouth on the back of her head.
- Karai is 1/8 Chinese through her mother Tang Shen, who was 1/4 Chinese through her grandfather.