The Dead Demon King and the Crazy Hero

He completed his mission and killed the devil. Those in power kill the "brave". The holy sword was taken away, the blessing became a shackle, and a soul contract prevented him from wielding the sword against the royal family again. It's called reward, but it's actually exile. Until he followed the clues and dug up history that had been buried for thousands of years. Until he understood that the mission he had been taught was false. So, when the kingdom's cavalry surrounded him again and accused him of being a "mad brave"—— he smiled He raised the long sword that no longer shone with holy light, faced the dark royal flag in front of him, and made a declaration: "Behold, this is what you have created with your own hands... The next Demon King."