I Reincarnated as a Demon King,I Will Kill Everything

After slaying the Demon King, Hero Neil expected peace—what he got was betrayal. His comrades stabbed him in the back. His beloved abandoned him. The very humans he protected… turned against him. But death was not the end. Neil awakens in the body of a powerful Demon King, reborn in the very darkness he once fought to destroy. With hatred burning in his veins and a second chance carved by fate, Neil sets one goal: To wipe out humanity. To reclaim the world they stole. And to become the true Demon King this world fears. Watch as the fallen hero turns into the nightmare of mankind—where light has no place, and vengeance is just the beginning.