|“White Belt, Black Heart”|
During his meditation, Splinter is contacted by his old mentor Mogo-san, who reveals that he is visiting New York and asks his old pupil to meet him. Splinter is somewhat anxious about leaving the lair, but he goes nonetheless.
Meanwhile, April covers a gang of criminal ninja who have been terrorizing the city, the Black Heart Gang, led by a man named Yoku. Shredder and Krang watch the report, and decide that they should get the strange ninjas to work for them.
Mogo is rather shocked when he sees that Hamato Yoshi has become a giant rat, but he soon reveals why he's in New York. He is bringing the sacred white belt of the Mogo clan, to pass it on to his grandson Yoku. Splinter isn't sure where Yoku is, but believes that the Turtles can help locate his sensei's grandson. After the Turtles are introduced to Mogo, Donatello reluctantly reveals to him that Yoku has become a criminal.
That evening, Yoku leads a raid on a jewelry store, while Shredder watches them with great interest. He approaches the ninja gang and easily trounces them, offering them Dimension X weapons in exchange for secret government plans.
April alerts the Turtles to the involvement of both the Black Heart Gang and Shredder, just before the Turtle Van nearly crashes into the Black Heart Gang's getaway truck. Just as they track down the Gang, they see Yoku shaking hands with Shredder, and break in to interrupt. Yoku uses a paralyzing weapon to immobilize the Turtles, but is shocked when he sees Splinter, allowing the mutant rat to get the upper hand.
The Turtles apprehend Yoku and bring him back to the sewers, where Mogo chastises him for what he's been doing. He gives Splinter the white belt and orders him to burn it, saying that it is better for it to be consumed by flames than given to someone who would dishonor it. Yoku then escapes.
April successfully manages to track down the Gang, only to be caught when her Turtle Com goes off. They decide to use April to get into the government facility Shredder wants infiltrated. That night, Vernon shows news footage of April driving the news van away from the crime scene, and the Turtles charge out to rescue her.
Meanwhile, Mogo decides that it has become too painful to stay, and prepares to leave New York.
When investigating a restaurant the Black Heart Gang frequents, Michelangelo accidentally uncovers a basement level, where April is being held captive. They easily defeat the Gang members, but are buried in rubble by a blast from one of the Dimension X weapons. It's then revealed that the president of a bank robbed by the Gang, Mr. Crocker, is actually their secret boss, but just as the Gang is about to kill the Turtles, Yoku unexpectedly turns on them.
After the Gang and Crocker are apprehended, Yoku says that he must speak to his grandfather, who is preparing to sail back to Japan. They barely arrive in time, and Yoku reveals that he's actually a government agent who infiltrated the Black Heart Gang. Mogo is delighted, but regrets that he asked Splinter to burn the belt. Splinter then reveals that he never burned it, knowing deep down that Yoku was honorable.
- Leonardo (Cam Clarke)
- Donatello (Barry Gordon)
- Raphael (Rob Paulsen)
- Michelangelo (Townsend Coleman)
- Splinter (Peter Renaday)
- April O'Neil (Renae Jacobs)
- Burne Thompson (Pat Fraley)
- Shredder (James Avery)
- Krang (Pat Fraley)
- Bebop (Barry Gordon)
- Rocksteady (Cam Clarke)
- Yoku (Brian Tochi)
- Master Mogo-San (Pat Fraley)
- Mr. Crocker (Peter Renaday)
- Vernon Fenwick (Peter Renaday)
- Turtle Lair
- Channel 6
- Pier 17
- Mid-City Bank
- Jewellery Warehouse
- Golden Buddha Restaurant
Home media releases
- Teenage Mutant Ninja Turtles: The Legend of Koji
- Teenage Mutant Ninja Turtles Season 7
- Teenage Mutant Ninja Turtles: The Complete Classic Series Collection
- In the first shot of Krang watching April's news report, his robot hands are flesh colored instead of the usual red.
- When Donatello drops the sushi and Master Mogo-San catches it with his sword, he hands the sword to Leonardo. The sword instantly vanishes in following shots.
- After Bebop and Rocksteady finish painting the Technodrome and Bebop slaps green paint onto Rocksteady's shoulder, the green paint on his own shoulder disappears in the next shot and then reappears two shots later.
- When Rocksteady gives the communicator to Krang so he can talk to Shredder, the green paint on Rocksteady's shoulder from earlier has disppeared.
- When Rocksteady gives the communicator to Krang so he can talk to Shredder, Krang's robot hands are flesh colored again.
- Raphael's colors suddenly change into Leonardo's colors when the turtles are escorting Yoku into the Turtle Van.
- Raphael disarms one of Yoku's men by throwing one of his sai and pinning the thug's weapon to a wall. In the next shot, his sai is back on his belt.
- Final episode where Shredder is voiced by James Avery.