The secret club at a prestigious girls' school where a young girl dreams of finding someone strict enough to truly punish her. This is the "Punishment Club." Alone in the empty clubroom, Mio Ichijo indulges in masturbation. One day, she discovers sadistic potential in the newly transferred Ai Mukai and begins desperately pleading for punishment. Subjected to increasingly harsh discipline every day, Ai gradually awakens to the pleasure of domination. Through deep-throat with a strapon, piss drinking, slapping, BDSM training, and various other forms of punishment, Mio Ichijo experiences her first lesbian encounter and embarks on a journey of masochistic awakening.