The 4th installment of this popular series features exclusive Ai Sayama! Night after night, Ai's crotch aches with the intense moans and passionate, animal-like mating of flesh. Her father-in-law may be old, but he has a strong libido, and every night he makes love to his mother-in-law. He's a viper-man who will stay active his whole life. In comparison, her husband is indifferent when it comes to sex. The frustrated wife's Kokoro gradually turns to her father-in-law. She wants to be held like that. Unable to suppress her desire, she goes to her father-in-law on her dangerous day to be held by him...