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

A young man leaves his rural home to pursue a life of adventure, quickly advancing in the city before meeting his end in a dungeon beyond his skill. As he dies, his blood merges with the essence of a recently slain dragon. Centuries later, he awakens as an undead being, possessing immense power and a distinctive appearance. Though feared for his kind's cold nature, he retains his former personality and memories, including his quiet demeanor. Despite his overwhelming strength, he has no desire to use it, instead seeking a way to end his existence. He travels through a changed world, encountering figures like necromancers and dragons, none of whom can harm him.