"The world where the hero is summon" Being use only for one purpose, is kill the Demon king, without even a little support Or even fund's, all the human is hostile to him after he killed the demon king, he been  Invited to the world conference, that will kill him he didn't appear, the cost is all of his skill, that he honed over a decade's, and he been treated As a Rebel, he decided to become the next  Demon king, and conquer the world and kill all The human beings, and to do that he Need to plunder, the hostile monster  Or some that while get in his way, In the future and gain A comrades along the way.