Shumi, who was tired of her husband's selfish and rough sex, began to feel sympathy and fondness for her son, Yuki, who had been watching the couple's activities. One day, Shumi witnessed Yuki masturbating with his own panties. Pretending nothing had happened, after Yuki left, Shumi tried to comfort herself to dispel her troubled thoughts. Yuki, returning home to retrieve something he forgot, accidentally saw his mother and attacked her. Knowing it was a line that should not be crossed, Shumi still accepted Yuki. The secret affair between mother and son, hidden from the husband... ahead lay days of parental sexual depravity...