Kyoko and Yuko's husbands can't go, so they come to the hot springs by themselves. They immediately go into the open-air bath, and while they're fooling around, touching each other's huge breasts, suddenly two men enter the bath. They hastily hide their voluptuous bodies and try to leave, but when the men offer them some sake in the bath, Kyoko and the others accept the invitation, as they are disgusted by their husbands. Then, after getting moderately drunk, the four men and women generously combine their bodies in the open-air bath where they just met...