Nana, who lives alone with her father who often goes on business trips, almost lives alone.She was a quiet and honorable female student, but she has a delusional habit, she imagines sex with an old man, and she indulges in masturbation.One day, she is attacked by her neighbor, Masakazu, who brought a circular, and has sex with her.As a result, Masakazu's older brother, Taro, and Taro's boss, middle-aged delinquent Hirai, take notice of her, and she falls into a life of debauchery...