Ichika was introduced to her mother by her homeroom teacher, Riku. Ichika has a steady stream of boyfriends, but she's always been in love with Riku. Ichika kisses a drunken Riku at home. Riku is attracted to Ichi, who is the daughter of his dating partner and his student, even though he thinks he shouldn't get involved. And Iichika, who wants Riku to be her own, draws out Riku's true nature through reverse anal torture and teaches her that she is the only one who can accept it.