Mahiro is under constant pressure from her mother-in-law to produce a grandchild. Before a family hot-spring trip, she is ordered to abstain for a month to improve her chances of conceiving, only for her husband to reject sex on the night they arrive. Her father-in-law is likewise turned down by his wife. Both frustrated and desperate for release, Mahiro and her father-in-law head to the baths, where he catches sight of her naked and can no longer restrain his desire. Over the trip, he repeatedly creampies her and leaves her fearing she has been impregnated by him.