Gotou Hajime, has enrolled in Penile University, majoring in perversion, in order to study and deepen his understanding of the art, and eventually carry out research on the subject.
Tatsuya is a college student and classmate of Saki as well as her lover. However, he has a special “cuckold” fetish, which one day becomes known to Saki. “Are you interested, Taku-kun? I’m going to have sex with other people.”