Fuufu Koukan: Modorenai Yoru

The story follows two inseparable couples: Asuka and Kousuke Mihara, alongside Akana and Reiji Suzukawa. Bound by a deep-rooted friendship since their university days, they have shared every joy and sorrow of life. However, beneath the surface of their unbreakable bond, hidden cravings and the creeping boredom of marital routine have begun to take hold.

Their world shifts during a joint getaway to a secluded Onsen resort. Amidst the heady influence of sake and the ethereal, swirling steam of the hot springs, a daring and transgressive proposal is voiced: Couples Swapping.