Nina faces constant pressure from her in-laws to produce a grandchild. One day, her father-in-law suggests that the whole family take a hot-spring trip. To improve the chances of conception, her mother-in-law orders her to abstain from sex for the entire month beforehand. Yet on the day of the trip, Nina's husband unexpectedly refuses her. Her father-in-law is likewise rejected by his own wife. Both left painfully aroused, Nina and her father-in-law head to the baths to calm down—and he happens to catch sight of her bathing...