His father-in-law suddenly asks him to abstain for a month before the family hot-spring trip, hoping he will use the getaway to try for a baby with his wife. He follows the request, but his pent-up desire becomes unbearable. While heading to the baths to cool off, he accidentally enters the women’s side and sees his mother-in-law’s alluring naked body. Losing all restraint, he spends the trip repeatedly creampieing her and leaves with a secret he could never confess to his wife: he has impregnated her mother.