There Once Upon a Time There Was a Demon King

He conquered the world and achieved the position of Demon Lord, but his life was filled with loneliness and sorrow. The whole world is an enemy, and he kills decisively. He climbs to the top of the Supreme Being by stepping on the corpses of countless enemies. When he looks back, there is no one around him. Relatives and friends are all dead, so the old ones will last forever. No matter how powerful you are, you can't save a moment of warmth; even if you keep peace in the world for tens of thousands of years, you can't keep an inch of the old shadow in your heart. He is the protector of the human race and a lone traveler in the eternal night - under the legend, there is a sorrow that no one knows.