Yumiko has been married to her husband for 20 years. After their son grew up, they had sex as a couple. However, she couldn't be satisfied with her husband whose physical strength had declined. Still, she wanted to climax through sex. A few days later, her husband suddenly announced that he would go golfing the next day. Yumiko was comforting herself alone in the kitchen. Their son came home and saw the kitchen, startled and rushed into his room. The next day, Yumiko was cleaning the floor. Unable to bear what he had seen the previous day—his mother masturbating and her shaking butt—their son…
