Ayumi marries a divorced father nearly twice her age and enjoys a happy new life, but she worries about his adult son Kodai. He has dropped out of school, refuses steady work, and resents her attempts to lecture him as his new mother. With a young, beautiful woman suddenly entering his previously all-male home, his anger and pent-up lust explode into a dark stepmother-and-adult-stepson role-play in which Ayumi is overwhelmed and ultimately conquered by pleasure.