Persona
Demon is an Akuma (an evil kind of kami) masquerading in the human realm. He is the former vice-king of Jigoku (Hell) and the founder of Akumakyō (a demoniac religion).
Kogure preached his "religion" as the leader of Seikima-II (聖飢魔II, seikimatsu?, "end of the century"), a religious group whose aim is to conquer the earth via heavy metal music.
In 2007, he changed his recording label to Avex Trax, and in mid-2009 changed his persona to Demon Kakka ("His Excellency Demon").
Read more about this topic: Demon Kakka