Eriko, a mother, has finally finished raising her beloved daughter Mahiru, whom she raised alone. They were supposed to be happily married, but after a while, Mahiru comes to her for advice about Tatsuro's infidelity. When she calls him in to tell him the story, he suddenly confesses, "I love my stepmother." From that day on, Eriko begins to use her as an outlet for his twisted love. She tries to convince Tatsuro that this can't continue forever, but...