The members of the Futanari Club travel to the Manra Valley hotsprings to research the local harvest festival for a school project. Things quickly get out of hand though, as the hotsprings act as an aphrodisiac...

Dissatisfied with an ordinary high school life, Akane Niimura decides to join the Futa Club. The organization consists solely of futanari—well-developed women with male genitals. The club's members spend their free time pursuing a single activity: indulging in as much sexual pleasure with each other as possible. However, there is a major problem with Akane—she is a regular girl! Therefore she can only be admitted to the club as a "service specialist." Despite ending up with the subservient role of being a sex toy for the other members, Niimura is content with her position and resolves to fully enjoy the club's exciting activities.