sumire, a new bride, is pressured by her mother-in-law to have a grandchild soon. one day, the family decides to go on a hot spring trip. however, sumire is ordered to abstain from sex for a month leading up to the trip. on the day of the trip, sumire is not satisfied with her husband's mechanical sex. meanwhile, her father-in-law tries to have sex with his wife but is rejected. the two, overwhelmed with sexual desire, head to the hot spring to calm their bodies. then, sumire's father-in-law accidentally sees sumire bathing...