壁の向こうの妻の嬌声２ ～隣で激しく腰を振る汗だくの妻は、絶頂の果てに白濁汁を注がれ淫らなイキ顔を上司に魅せる～

The apartment where the protagonist and his wife live was caught on fire. So until they can find a new home, they will have to live with his boss' family for while.

Because they can't have sex in another person house, the protagonist is a little bit sexually frustrated. One day, his boss confesses that he has erectile dysfunction​ and asks him to sleep with his wife.

And thus, the swapping story begins.

[Translated from Official Site]