壁の向こうの妻の嬌声 F 〜かつて戯れあった俺たちは、交錯する淫宴とともに肉欲へと溺れゆく〜

Yuuto Tokunaga and his wife, Satsuki, find themselves with new neighbors: Koudai and Ria, a married couple whom they're also friends with.

Having gotten along since their student days, the four of them begin drinking together and rekindling their old bond.

One night, Satsuki made a candid, drunken confession: "To be honest, Koudai, I used to have a crush on you back in our student days."
The delighted Kodai replied, "Actually, I was interested in you, too."
Ria then followed suit, revealing, "Truth be told, I had a crush on Yuuto."
Flustered, Yuuto admited that he, too, had liked Ria.

"So, why don’t we all kiss each other?"

Ria suggested, perhaps spurred on by the alcohol.