JUQ-413 Mariko Sada is invited by her mother-in-law who wants her son-in-law's big dick all the time.

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 sub-standard big dick she happened to see, told herself that she was doing it to vent on her daughter's behalf, and continued to secretly seduce him whenever she had a chance, day or night. And Shinji can't resist the lustful charm exuding from his stepmother, and continues to be played with his cock over and over again...