Night after night, the intense moans and the passionate, beast-like sounds of flesh colliding made Mari's pussy ache. Despite his age, her father-in-law is a sexual powerhouse who fucks her mother-in-law every single night—a lifelong, active "viper man." Compared to him, her husband's sex is bland. The frustrated housewife's heart gradually shifts toward her father-in-law. She wants to be fucked as intensely as that. Unable to suppress her desire, Mari goes to her father-in-law on her fertile day to be fucked by him...