I Am the King of Demons in the Age of Demons

A hundred years ago, the earth was connected to the world of demons. Demons descended on the earth, and countless humans turned into food for the demons. Until humans used demon genes to develop two major systems, the God's Favorite and the Demon Controller, and used demonic power to fight against demons! After a young man from Earth died, he obtained a buggy demon enhancement system and entered the body of a demon. He used the power of the system to become a demon and fight against demons.