While living with her daughter's family, Maki one day accidentally sees her son-in-law Kenichi's unbelievably large penis. Since then, she can't get his huge penis out of her head and spends her days in distress... At that time, she witnesses Kenichi masturbating. It seems that he and her daughter are sexless, and feeling sorry for his situation, Maki thinks, "Then I'll take my daughter's place..." and skillfully seduces Kenichi, sucking on his proudly erect huge penis...