There's a fitness club spreading rumors that anyone can achieve an incredibly fit body just by joining. Working there as an apparently ordinary instructor, Reiko Kobayakawa utilizes a unique membership management system to deliver rigorous yet enticing training programs. Her special method for boosting members' motivation is an unconventional system: using her alluring ass as leverage, she forces members to wear chastity belts and grants the reward of ejaculation only to those who achieve results. Day after day, members dream of earning that reward, pushing themselves to the limit in the gym.