Schoolgirl Ririka transfers to a school where her uncle serves as the disciplinary officer. At the invitation of her classmates, she takes on the role of manager for the boys' gymnastics club. Unlike her previous all-girls school, this new environment carries a slightly masculine atmosphere, and Ririka begins to feel unfamiliar sexual excitement. By chance, she sniffs the gym clothes of a male student and becomes deeply aroused. Unable to control her arousal, she masturbates in the bathroom. This intense sensation marks a completely new experience for her.