Incubus x exorcist
My rating: 8,2/10
This is really hot. The ML is just gorgeous and they don't leave out any details. But beware of the FL getting raped by a strange tentacle demon.
EXORCIST, DEMON, CONTRACT
The heiress of a shrine of exorcists gets saved
from a demon she tried to kill by her classmate who turns out to be an incubus. They end up making a contract about him helping her defeat demons and her giving him power by sleeping with him.
Madoka Exorcist