The main character, Lent, has been a copper-cla.s.s adventurer on the frontier for countless years. By a stroke of bad luck, he ran into a ma.s.sive creature in the depths of a labyrinth, lost, and awoke as a bony {skeleton}. After anguis.h.i.+ng over being unable to enter any towns, he recalled how creatures could evolve themselves, and deciding to obtain a new fleshy body, he set out to defeat the creatures in the labyrinth.