Ore to Maou no Love Love Keiyaku

Ritsu Kido, your average office worker, is the grandson of an exorcist who once made contracts with demons to expel evil spirits. After a night of drinking, Ritsu awakens to a used condom in his bed and is puzzled.
He looks around the room and sees a man with horns and wings covering himself with a blanket, glaring at him...

Holding his head in his hands with a splitting hangover, Ritsu recalls the events of the night before.
It turns out, the man in his room is actually a demon he summoned named Ryan, and the two of them have entered into a contract by sleeping together. Moreover, this contract can't be broken so easily! This is a romcom between an average office worker and a prideful tsundere demon!

(Source: Renta!)