Kunitoshi Joukyuu is a lazy, shameless aikido prodigy, by reputation the strongest fighter alive, except that his father sealed away most of his power before dying. A struggle for control has turned a local high school into a battleground, and Rin Kizuki, granddaughter of the school's chief director, comes to him for help. Joukyuu takes the job with as little effort as he can manage, drilling the girls who line up under him into real martial artists while he hunts for a way to break his father's seal.