Yu exercises with a balance ball given to her by her son to prevent back pain. At that time, he loses his balance and gets on his son. The son, who felt a woman in his sweaty mother's body, was embarrassed and ran away. After that, her husband comes home and hugs Yu, saying, "It's erotic." It felt good to be a married couple for the first time in a long time, but Yu's body wanted more. Then Yu started masturbating. My son, who saw it, was excited and hugged me ...