Natsuko's son, Kousuke, whom Natsuko raised splendidly on her own, has finally decided to marry. However, Kousuke, who had a secret admiration for his mother, could not shake off that feeling until the very end... On the night before the wedding, Kousuke, who is worried about his new life, gives his last lesson to his son, saying, "I just want the two of you to be happy...". Kousuke, who has climaxed many times with unconditional love, continues to experience the pleasure he feels for the first time, and his excitement continues to pile up. And the mother and child who dabbled in forbidden pleasure are trapped in a whirlpool of desires.