After saving the world, Leo becomes the new object of scorn from the kingdom. After receiving the king's kind of apology, Leo is off to be obscure in the world. When one day, the Demon Lord's army is recruiting new people to help rebuild the demon domain. Thus Leo has a brilliant idea. He will join the Demon Lord's army, the very army he defeated not too long ago. He will help them fix all the problems he caused. After all, the humans do not really appreciate what he did.