Maki lives with her daughter and son-in-law. One day, she accidentally sees her son-in-law Kenichi's unbelievably large cock. From that moment on, she can't get his massive dick out of her mind, and begins suffering in restless longing. Then one day, she catches Kenichi masturbating. Feeling sympathy upon realizing her daughter is in a sexless marriage, Maki decides to seduce him. Soon, she finds herself unable to resist and starts greedily devouring her son-in-law's huge cock, taking her daughter's place.