Reiko Kobayakawa, a grieving widow raising her son Ichiro alone, struggles with loneliness and pent-up desire. One day, she discovers adult magazines featuring mature women in her son's room. Realizing he is aroused by women her own age, conflicting emotions stir within her. After witnessing her son masturbating and seeing his erect cock first thing in the morning, Reiko's emotions reach their breaking point. As shock and lust collide, the story descends into forbidden territory, unraveling a tale of incestuous desire between mother and son.