Erebus

Erebus

When someone has a strong wish for something sinful, the master of shadow will appear in front of them and make the offer to help them fulfill their wish. Accepting the offer means doing the contracting.  After being a contractor of the master of shadow and fulfilling their wish, the contractor will get some shadow-like mark on their body and gradually lose their personality. In the last, they will become a shadowill, servant of master of shadow.

Erebus has become a shadow for a long time and he can't remember his former self.

He is a cool and calm man who always seems to be mysterious. It's hard to know what he is thinking now. There is a rumor that he will become the next master of shadow.