Newlyweds the Asano couple and the Yamamoto couple have each married younger wives and lived together as kind, sincere partners. However, both gradually developed a desire to explore their hidden sexual desires and decided to enjoy NTR together as a couple. To fulfill this fantasy, they consulted an organizer of an orgy group and requested the planning and filming of a swapping party. Surprised by the unusual request, Ayumi and Rui head to a hot spring resort to participate with their husbands. There, amid the rising steam, the gathering descends into a maddening party of couple-swapping and wild group sex.