Tada no Shikabane no You da to Iwarete Ikuseisou, Kizuitara Saikyou no Undead ni Natteta

Zion, a daring lone explorer, entered a dungeon beyond his capabilities without hesitation. Regrettably, it would be the final endeavor he pursued. Roaming through the dungeon for countless years as an undead, he relentlessly battled scores of monsters until his undead form underwent multiple "evolutions." Upon recovering his consciousness, he emerged as the mightiest undead: the "No Life King." The appearance of a new catastrophic monster that threatened the world prompted humankind to experience overwhelming terror and plunge into despair. "The end of the world is upon us," they thought. However, this is a story of the living who shook in trepidation and the undead who never intended to bring about the world's destruction.