Mitsu was the leader of the rebellion against Lord Norinaga in TMNT III. Mitsu was also the granddaughter of the village elder, and the big sister of a young Japanese boy named Yoshi, who was saved from a fire by Michelangelo. She had a mutually romantic relationship with Norinaga's son, Kenshin. Further complicating matters, Michelangelo was smitten with Mitsu, but it was obvious Mitsu was not interested. Nevertheless Michelangelo wanted to remain in Japan with her before deciding to return to New York.
At one point, Yoshi (who grew very close to Raphael) gave the Turtles the time scepter, which led the Turtles believe that Mitsu told her brother to hide it so they'll have to fight Norinaga in her stead. Being accused, she walks out the room in distress. Soon her grandfather came in to confess he told her grandson to hide the scepter and begs the Turtles to help the village fight Norinaga so her granddaughter wouldn't have to. The decision was made for them when Whit betrayed them and kidnapped her.
After Kenshin and his father's men are returned to their normal time, Mitsu and her village people decide to put a truce with Lord Norinaga and conclude to have peace. As they leave, Kenshin pulls Mitsu aside, much to her surprise. They both share a kiss, now able to show their relationship in the open.
Weapons and abilities
Mitsu was skilled in the use of the longbow and dagger. It seems she is also proficient with other weapons, including the Time Scepter.
- An action figure of Mitsu was released, designated "Movie III Princess Mitsu". Her accessories included a Time Scepter, longbow, quiver, dagger, and knife.
- Digging around the coding for the beta of the Super NES version of Teenage Mutant Ninja Turtles: Tournament Fighters reveals that Aska was initially named Mitsu. The change likely occurred due to the third film's poor performance.