Momoko is a father-obsessed girl living alone with her dad after her parents' divorce. At school, her homeroom teacher mysteriously accuses her of cheating and, threatening to keep it a secret, repeatedly pressures her for sex—until one day, he ambushes and forcibly rapes her at home. That night, sneaking into her father's room, Momoko overhears moaning from the other side of the door and realizes he's masturbating. In a panicked moment, she strips off her clothes in front of him, giving in to their forbidden relationship.