Horde: Dark Contract Saga

Obi is just an average high schooler who needs money for a date with the girl he likes. But when he signs a contract for a part-time job with a shady boss, he isn't prepared for the fine print… bringing the souls of the damned under heel! With new powers and more to his past than he realizes, he will have to become stronger in order to save the girl… and the world! Source: Webtoon