Eriko poured all of her love into her only son, Shinichi, even refusing to live with her husband. However, as Shinichi grew older, the two began to seek each other's bodies. One day, her brother-in-law, Toshio, visits her house. Toshio learns of the fact that she has no sex with her husband, and Eriko looks at her with curiosity and even plays with her body... Unfortunately, Shinichi sees the scene. Seeing the lewd appearance of his mother, who he thought was only for him, Shinichi's cock became as hot and hard as ever...