Rin, the mother, burns with desire, yet her husband is indifferent. As a result, Rin constantly suffers from sexual frustration. Yosuke understands his mother's pain but, recognizing his role as her son, believes there's nothing he can do and chooses to ignore it. However, upon seeing the lonely expression on Rin's face while she masturbates, Yosuke makes a firm decision in his heart. He realizes he is the one who can truly satisfy her—his own way of showing kindness. Rin, telling herself it will happen just once, agrees to accept her son Yosuke. But Yosuke, inheriting his mother's passionate bloodline, turns out to be a stamina monster capable of driving her into ecstasy beyond control.