In order to support my wife, whose due date is approaching, my wife's mother-in-law, Marina, is coming to Tokyo. Thanks to her, her family relationship is also good. A few days later, when she was hiding in the bathroom and masturbating, Marina suddenly opened the door. I was shaken by the sudden turn of events, but Marina-san, who knew about the situation, seemed apologetic and asked if I could help. And she made an unexpected proposal...