Five years ago, Shiori, a student at the time, ended up having a relationship with her cousin Masashi after a bit of impulse. However, they didn't actually have sex, she just taught Masashi how to masturbate, who didn't even know how to do it at the time. They were both a bit strange at the time. Since then, things have become awkward between them, and Shiori has always kept her distance from him. Years have passed since then, and the two are reunited, but... Shiori's cousin's monkey-like sexual appetite drives her body crazy!