Nozomanu Fushi no Boukensha

Rentt Faina has spent 10 years as a Bronze-class adventurer, gaining plenty of experience but never the talent needed to reach the rank he dreamed of. While exploring a labyrinth, he wanders into an unknown area and is killed instantly by a dragon. Yet Rentt wakes again inside the same dungeon, now transformed into a skeleton, one of the weakest forms of undead.

He discovers that killing monsters allows his body to evolve into stronger undead forms and may eventually let him resemble a human again. Armed with the experience of his old life but unable to reveal his identity, Rentt begins climbing from the very bottom once more, hoping that in death he can finally reach the heights that remained beyond him while alive.