Shinya hasn't had sex with his girlfriend Yui for a long time. After many pleas and persuasions, she finally agrees to let him have sex with her next week. Finally, after a long wait, the day has arrived! He rushes into Yui's house and finds her seemingly asleep. Unable to resist any longer, Shinya immediately has sex with her! But when he sees the face of the person he is having sex with, he is shocked, as it's not his girlfriend! When Yui returns, Shinya realizes that it's her mother, Rio. Rio coincidentally came to visit her daughter and never expected to be screwed by her daughter's boyfriend like that. She is not only not angry but also feels excited and satisfied. Due to the long-standing discord between the wife and husband, she has not been satisfied sexually for a long time. Shinya, with his large and strong manhood, continuously brings Rio to climax, something her husband couldn't do for her. Since then, taking advantage of this situation, Rio constantly makes Shinya have sex with her, satisfying her sexual desires, and Shinya himself can't resist the alluring body of the potential future mother-in-law...