A brief description of the manga I Will Quit Being the Hero:
That’s how you save the world, and suddenly you realize you have no place in it. It’s not a good conclusion for a hero who fought for people. But Leo realizes that now his fantastic power will be of no use to the human world: it’s dangerous because it’s too big. Where to go, where to find its use? Can Leo only realize himself in the camp of the enemy? That’s what demons will be happy about!