Hina is a schoolgirl. She recently got a boyfriend and is a quiet, good-student in a pure relationship, but she has delusions and imagines having sex with older men and indulges in masturbation every day. She likes her boyfriend, Yugo, but she just can't bring herself to have sexual feelings for him... One day, she is attacked in her sleep by Koji, a man from the neighborhood who brought her a notice, and they have sex. This leads to her falling into a life of debauchery, along with Koji's drinking buddies.