University student Yukihiro Yanagihara is part of the men's rhythmic gymnastics club at his university, but is left to pack up after his juniors. Even though he doesn't stand out much, he has a childhood friend, Minori Tsubokura, who calls him onii-chan and looks up to him. Minori aspires to be like Yukihiro and joins her high school gymnastics club, but she doesn't do as well as she wants. That's where Minori pleas for Yukihiro to coach her, and when they start training, an unexpected sexual accident happens. This training seems to have worked (?) And Minori improves and earns a spot on the competition team. With this accomplishment, Minori introduces Yukihiro to the other club members in attempt to get him as their coach, but...
