Dark Summoner to Dekiteiru

ダークサモナーとデキている

Amona, a dark summoner and demi-human who uses demonic powers, is the newest addition to the party of the uptight cleric Roni. Everyone expected the two to dislike each other and to have nothing to do with each other. But to their surprise, on their first day together as an adventuring party, they had a one-night stand...! (Source: Comic Dragon Age, translated)