She was the leader of the Japanese rebellion army against Lord Norinaga. 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 City.
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 his grandson Yoshi 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 Honor Guards are returned to their normal time period, 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, knife 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".
- Digging around the coding for the beta of the Super NES version of Teenage Mutant Ninja Turtles: Tournament Fighters reveals that for the alias was Aska was initially named Mitsu. The change likely occurred due to the third film's poor performance.
- Her name in Japanese "Mitsu" means "Three".