Wife Hitomi is on a solo trip, enjoying some time away while her husband is busy with work. Today, she's arrived at a renowned hot spring inn for a two-day, one-night stay famous for its outdoor baths. Located by a quiet riverside, this historic ryokan employs her former university wrestling club senior, with whom she once dated. Though they usually meet at love hotels for their affair, today she's decided to switch things up by visiting him under the guise of a vacation—though her real intention is sex. Soon after, other big-titted married women, proud of their assets, arrive individually at the inn. They check in with eerie, knowing smiles, as if plotting something devious. Before long, they begin outrageous actions, throwing the entire inn into chaos.