Mariko, who is frustrated due to lack of sex with her husband, secretly consoles herself during her troubled days. One day, she finds out that her son-in-law, Shinji, who lives with her, secretly masturbates for the same reason... Mariko, who was captivated by the substandard big dick she happened to see, told herself that it was to make her vent on behalf of her daughter, and she secretly took advantage of him day and night. He continued to tempt her. And Shinji can't resist the lustrous charm that exudes from her stepmother, and continues to be played with his cock over and over again...