Some TMNT stuff really isn't for little kids.
Splinter first appears when the Turtles try to secretly return after a battle with some Foot Clan thugs in the subway without alerting Splinter. However, he manages to catch them and punishes them by making them maintain balance on certain items until they tell him why they were out on the streets.
Splinter breaks Mikey by tempting him with a slice of the 99 cheese pizza, and Mikey admits they were out fighting the Foot Clan and when he mentions April's name, Splinter is alarmed and orders the Turtles to go find her.
Later, when the Turtles bring her into the Lair, April meets Splinter, who remembered April before he mutated, when he and the Turtles were ordinary test animals in a lab manned by Dr. O'Neil and Eric Sacks. April used to videotape herself in her fathers lab when she was little, and loved Splinter and the Turtles, personally naming them and feeding them pizza, which they all loved.
However, Dr. O'Neil learned that Sachs was up to something evil, and burned the lab down, at the cost of his own life. April saved Splinter and the Turtles, and took them to the sewers to be safe, with Splinter alone possessing enough intellectual ability at this time to remember April and her kindness. The mutagen soon took effect, granting Splinter and the Turtles enhanced intellect and anthropomorphic bodies.
Remembering the example of Doctor O'Neil's love for April, Splinter decided to raise the Turtles as his sons. The boys were always curious about life above the surface, but Splinter tried to keep them away, but soon realized they would need to protect themselves. One day, he stumbled upon a book about the art of Ninjutsu, which he used to teach himself the art, before passing it down to the Turtles. When they were ready, he armed them with their trademark weapons. Having told this story to April, Splinter expresses his thanks to her for protecting them.
However, soon after, The Foot infiltrate the lair- unintentionally alerted to the Turtles' continued existence by April talking to Sachs before she learned that he was a threat- triggering an alarm that alerts the Turtles. The Foot Soldiers break in with a bomb and blow the place open. The Turtles fight the Soldiers, and Splinter gets in on the action himself. Shredder enters the lair, decked out in a new armor. He faces off with Splinter, who dodges Shredder's knives and gets a few good hits in.
Splinter blocks the Turtles from joining in, in order to protect his sons, but they lift themselves up in time to see Shredder grab Splinter and hold him before the Turtles, threatening to kill him if they don't lay down their weapons. They do so, but Shredder still hits Splinter hard enough to take him out, while the Soldiers cattle-prod Leo, Donnie, and Mikey, capturing them and then blowing the lair up. Raph emerges from the rubble and goes with April to take Splinter to rest. He pleads with Raph to save his brothers and stop Shredder.
Later, after escaping, and stopping Sacks and Shredder, The Turtles use some mutagen to revive Splinter, who tells them he is proud of them.
A year later, Splinter has become notably older, with his hair now greyer than the previous film. He is initially shown attempting to complete a twenty-four meditation session to achieve enlightenment, but the Turtles interrupt him with a second to go when they learn that there is a plan to break Shredder out during a prison transit. When the team becomes divided after discovering a mutagen variant that could conceivably make them human, Splinter consoles Leonardo to remember that the team is strongest because of their different points of view, rather than because they all think the same way.
Splinter wears a yellow robe and a black belt with a medal on the front. His hair is graying and in a Japanese bundle.
- When Splinter is telling April about how he raised the Turtles there's a scene in his flashback where Leonardo appears slicing pizza in the air for his family and one of the pieces hits Splinter in the head is a reference to the 1990 film, where the same thing happens.
- Splinter and the Turtles were laboratory experiments, much like in the IDW comics origin story.
- This incarnation appears to have a strong prehensile tail. This is evidenced by being able to use it to pin one of the Turtles to the wall and spin the objects they were balancing on.
- Unlike other versions of the character, this Splinter has no connection to Hamato Yoshi.
- The book Splinter found on ninjutsu is written by Eastman and Laird.
- Splinter's face is based on Toshiro Mifune.