Keisuke

A boy who has a thing for her sister's underwear, which would eventually get him caught by none other than his sister. As a result, he is forced to cross-dress, masturbate, and have sex with his sister, subsequently being blackmailed by Kotomi, Keisuke's friend and classmate, into having sex with her as well, to prevent photographs of him in girl's attire from being seen throughout the school they study in. Keisuke's sexual relationship with his sister would later be discovered by none other than Kotomi in the public bath.