A busy husband who remarried and a stepson who has become a shut-in... 'Akari,' who is happy but also feels a sense of loneliness after marrying the person she loves, accidentally witnesses her stepson Kazu's masturbation. Unable to hide her shock and excitement at seeing his young, erect penis, Akari locks herself in the toilet, masturbating while fantasizing about sex with Kazu. Learning that Kazu became a shut-in because he was dumped by a girl, Akari decides to help him overcome his trauma by getting used to touching a woman's body. With her workaholic husband, Akari has been sexless, and she finds it cute when the awkward Kazu touches her breasts, eventually showing him her feminine side. They merge through bare penetration, and Akari finds Kazu's relentlessly thrusting 'hard penis' incredibly pleasurable. As Kazu becomes engrossed in the sex he just learned, Akari regains her womanhood... Sharing their guilt towards her husband, the two indulge in each other's bodies day after day, ultimately crossing the parent-child boundary and falling into a taboo incestuous relationship...!!
