TOKYO, JAPAN... Masahiro Takaguchi is a senior in high school preoccupied with his college entrance exams. One day, while returning home for summer vacation, he meets a mysterious girl on the train who seduces him and, in the course of a single train ride, changes his life forever. Mika Arakida goes home every night to an abusive stepfather and worthless, drunken, mother who cares more about protecting her monster of a husband than her own daughter. When Mika's stepfather forcibly breaks down her door and enters her bedroom one night, she fears the worst. But, luckily, Mika is well prepared...