When I met my cousin for the first time in a long time, she had become a grown-up... Five years ago, Nanami, who was attending school, had a relationship with her cousin Teppei due to a slight impulse. However, they did not have sex, she just taught Teppei, who had not yet experienced women, how to masturbate. They were both crazy at the time. Since then, things had become awkward between them, and Nanami had been keeping her distance from him. Time passed, and the two were reunited, but...