The Yamanouchi Ninja School is a secret ninja school founded by Toshimiru, who made the school in 338 A.D. carving it by using only the Lotus Blade, a mystical blade which will only change forms if it is wielded by one who has Mystical Monkey Power.
Master Sensei is the major teacher of the Yamanouchi Ninja School. This is also the school of next student:
- Yori, who befriended Ron Stoppable.
- Ron Stoppable, who was the Middleton High School Student, who was sent to spend a week learning at the Yamanouchi Ninja School, which was arranged by Master Sensei. He pretty much had failed every class at the school, even though he was connected to both the school and the Lotus Blade by destiny, due to his Mystical Monkey Powers.
- Rufus, who attended each class, along with Ron Stoppable, only he excelled at almost everything, unlike his owner, Ron.