The Demon King Overrun by Heroes

Synopsis

After diligently following the "demon king's standards," I ended up getting killed by the heroes. What, my tower and I are a custom-made hunting ground for heroes now? With this chance at life regained through regression, to hell with the damn demon king's standards! This is the story of surviving as the hard-headed(?) demon king, Berje! (Source: Naver, translated)