On the eve of her son's marriage, her mother became a woman.

Kosuke, the son of Natsuko, whom she raised in a great way on her own, has finally decided to get married. However, Kosuke, who secretly admired his mother, was unable to shake up his feelings until the end... On the eve of their marriage, Kosuke, who is struggling with his new life, gives his mother the final lesson to his son, saying, "I just want them to be happy..." Having experienced many climaxes due to unconditional love, Kosuke continues to experience the pleasure he has experienced for the first time. And the mother and child, who have tried to do forbidden pleasure, are eventually trapped in a vortex of desire...