Nozomanu Fushi no Boukensha

Rentt Faina was an eternal copper rank adventurer of frontier area named Lent.
He’s unlucky as he meets a powerful monster inside of the labyrinth, got defeated,
and when he noticed, he already became a bone man《Skeleton》. Agonizing since he can’t enter the town with his current condition,
he’s recalling about the existence of monster evolution, with a goal to gain a body with muscle, he defeats the monsters of the labyrinth.