One day, Maki, who lives with her daughter and son-in-law, happens to see her son-in-law Kenichi's enormous penis. Since then, she can't stop thinking about his huge cock and spends her days in agony... One day, she witnesses Kenichi indulging in masturbation. It seems that he is not having sex with his daughter, and Maki, feeling sorry for him in such a situation, skillfully invites Kenichi to "then I'll take my daughter's place..." and begins to suck on his manly, erect huge cock...