Erena Kurosaki, 38, a housewife. She lives with her husband and son, and has a good relationship with her husband—they still bathe together and enjoy sex. However, since her husband started working night shifts, she's been spending more time alone with her son at night. Being lonely, she unconsciously began relying on her son. As he's grown, he's become gentler, and now even joins her in masturbating together. Gradually, she fell deeply in love with him, cherishing his affection so much that she now loves her son more than her husband—a heartbreaking tale of forbidden passion.