Aika, a flashy-looking but family-oriented wife, married a divorced man with children despite the opposition of those around her. She had a good relationship with her stepson and the three of them lived happily together, but one day she was captivated by her stepson's erect crotch, something she had never paid any attention to before. After seeing his huge penis, Aika began to see her husband's stepchild as a member of the opposite sex... From then on, a twisted love relationship of incest with her stepson began.