Reiko is an overprotective mother whose only son is about to continue his education in the spring. When she learns that he has been accused of shoplifting, his recommendation and future are suddenly at risk. She begs the male teachers to protect his admission, and they offer a private settlement: she must serve them for one day. Reiko submits for her beloved son's sake, but during the humiliating training she gradually awakens to her own masochistic desires.