AKUMA GA KITARI KIMI NI MUCHUU

Akuma ga Kitari Kimi ni Muchuu summary:

Corporate slave Yuuto, under the influence of drunkeness, summoned the demon Morax. He made a contract with him where, in return of granting a single wish, Morax would receive his soul. Yuuto had used his wish to "become happy," and so began his comfortable life of ordering around a demon. However, Morax is the type of demon that feeds off of human bodily fluids and vitality. Because of that, Yuuto ends up having sex with him! They continue this strange cohabitation with a demon?!+