On a hot spring trip without their husbands, Kyoko and Yuko find themselves alone together. They head straight to the outdoor bath, playfully touching each other's big tits in high spirits. Suddenly, two men join them in the bath, surprised yet amused by the sight. Kyoko and Yuko panic and try to cover themselves, but when the men offer them drinks, they accept—both already fed up with their husbands. As the alcohol takes effect, the four begin intimately touching in the open-air bath. Tonight promises to be a special night.