The Demon Lord was defeated by Sage Dwight and the hero, and they successfully restored peace in the world. However, their success was short-lived, as rumors and suspicions spread about them potentially becoming the next Demon Lord. These accusations led them to be banished to the Valley of the Dead to die.
After a decade passed, Dwight managed to survive, albeit as a fleshless skeleton. Overcome with guilt, he cradled the hero's lifeless body and muttered to himself, "The problem is with the world itself. I must show them."
Determined, Dwight consumed the Miasma from the valley, transforming into a more powerful being than the previous Demon Lord. He then rallied countless undead followers, all with the sole goal of achieving world peace. As the new King of the Undead, he launched an all-out war against humanity, using his newfound power to ensure a better world for all.