Tachibana Yui is blackmailed into a secret, submissive relationship with her guidance counselor, Kuwabara-sensei, after he films her with her boyfriend, Kou-chan. To test her "devotion," Sensei forces her to wear a chastity belt throughout Kou-chan's baseball tournament, subjecting her to intense orgasm denial. Following the team's loss, Yui's desperation leads her to abandon her guilt and fully surrender to Sensei's control, admitting that her desire for him has eclipsed her love for her boyfriend.