The student council president Shiori Kousaka joins the weak competitive cycling club in order to increase the number of members.
Around that time, she spots a student heading to the back of the school building.
Thinking they might be suspicious, she follows them.However, it turns out to be a girl exposing herself...
Having viewed exhibitionism for the first time, Shiori's heart is set aflutter, and with energy participates in her first race.
After she easily wins, whether it's because she won, or because her chest is so large, she was drawing the eyes of all the male spectators.
Perhaps, just perhaps, that feeling in Shiori's heart was the same as that exhibitionist girl at the back of the school...