Book recommendation: "When a Hero Reincarnates as a Demon King" The plot of this book was very similar to the description in the question! The protagonist became the new Demon King, but he was cursed to use his power to resurrect the Demon King. He survived with the abandonment and pursuit of the whole world. The story spanned many worlds, reversing and deconstructing the story of the hero and the demon king. I strongly recommend this novel to you! I hope you like my recommendation. Muah ~