Mitsuko's daughter had gotten married and left home, but since both of them worked and housework was difficult, Mitsuko and her daughter decided to live together. Mitsuko had been alone for a long time and was frustrated, so she couldn't stop comforting herself. One night, when Mitsuko went to the living room, she found her son-in-law, who was supposed to be sleeping with her daughter upstairs, masturbating. The two of them see this and feel awkward. When I asked him about it, he said that it had been a while since he had spent any night time with his daughter. Mitsuko couldn't help but notice her son-in-law's big bulge and started rubbing it, saying I'd lend a hand...