The couple living in the same apartment engage in wife-swapping and NTR (Netorare) activities. Hitomi Ryou, Kato Ayano, SODx adult novel adaptation series, SDMU-825.

Ryosuke, who loves his wife's lower body but is unresponsive, lives in the same apartment building as Yuuji, who only caresses her casually. Seeking new excitement, the two husbands sign a contract to sleep with each other's wives. The wives, troubled by their husbands' unilateral decision, gradually become addicted to the lewd and twisted relationship…