Tower Dungeon 2

Tsutomu Nihei, master of the mysterious architectural monolith, brings his genius to bear on the fantasy genre for the first time. Having established himself with hit series like Blame! and Knights of Sidonia, he has now created a gritty, dark fantasy world and populated it with evil sorcerors and unique undead horrors.
The ingenuous farmboy Yuva must accompany a contingent of knights through the increasingly dangerous floors of massive tower on the way to  rescue the princess, Nihei bringing his unique sensibility to bear on a crumbling world of malformed creatures, wounded soldiers, and labyrinthine darkness.

Level 25 of the Dragon Tower—
Yuva and his companions, having fallen into a trap set by deserters from the Royal Guard, are grievously wounded and on the brink of annihilation. The traitors demand that Eriquo hand over the Dragonsbane, a legendary relic they seem to think he secretly carries… But even if they survive this deadly encounter, can our tiny band of adventurers really overcome the dangers of the indomitable labyrinth, defeat the Necromancer, and rescue Princess Ignelia? The gritty dungeon-crawling fantasy from science fiction master Tsutomu Nihei (Blame! , Knights of Sidonia) continues!