During the first millennium of his imprisonment, the Demon King thought, If anyone saves me now, I'll give them enough wealth to last a lifetime. But nobody came...
During the second millennium of his imprisonment, the Demon King thought, If anyone saves me now, I'll give them limitless power. But nobody came...
During the third millennium of his imprisonment, the Demon King thought, If anyone saves me now, I'll grant them three wishes. But still, nobody came...
By the fourth millennium... the Demon King decided he was better off relying on himself.
