Shoko lives with her husband and daughter. Although she lives a peaceful life, she is having sexless and unsatisfying days with her husband. At that time, she happened to witness her son-in-law, Toshio, masturbating...and Shoko was captivated by his gigantic cock floating in the darkness. She couldn't resist and seduced her all the time, wherever she was. Toshio, who was in agony after not having been with his wife for a long time, couldn't help but jump on her mother-in-law's lewd behavior, and before he knew it, he was looking forward to having sex with her...