Due to the appearance of mysterious spaces called “dungeons” all over the world, most people have awakened to supernatural abilities called “skills,” but the protagonist, a young boy named Yuga, has not awakened to any abilities. Yuga admires Jaeger, who uses his “skills” to explore the “dungeon,” but since he is powerless, he works as a “corpse disposal team (demolisher)” who disposes of the corpses of monsters that have been defeated, as a subcontractor for Jaeger for a small reward… One day, while “Jaeger” is disposing of the remains of a Cyclops that he had defeated, the monster that was not yet dead goes on a rampage, and the members of the corpse disposal team are killed one after another…! A mysterious being in the form of the Grim Reaper appears before Yuga’s eyes at the last moment! A heroic tale of a powerless protagonist who awakens to the forbidden ability of [undead transformation] and rules the dungeon as the strongest necromancer!