In Japan this can refer to:
① A person (or group of people) who works to repair the natural order of things that has been twisted and warped (by demons).
② A magic family or bloodline that refines their techniques in order to protect society.
③ The Demon Hunter Organization
④ As far as ① and ② are concerned, people in these categories generally don’t have powers that are suited to bringing harm to people. They generally remain passive/defensive when faced with a mixed-blood adversary who is on the borderline of being human.