When Shinji’s mother-in-law asks when she will finally see a grandchild, he is deeply unsettled. Following her instructions, he abstains for a month before the family hot-spring trip, only for his wife to refuse baby-making sex when they arrive. Restless and frustrated, he wanders the inn and accidentally sees his mother-in-law bathing. Desire overwhelms him, and during the two-day trip he repeatedly creampies her, ultimately leaving her pregnant with a secret he can never confess to his wife.