Tower Dungeon 1.

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.

An evil necromancer slays the king and carries off his daughter, secreting her in the legendary Dragon Tower. To save the princess, her steadfast Royal Guard assays the stronghold, but the way is blocked by powerful eldritch creatures… So, to supplement their forces in the face of mounting casualties, they press ordinary folks from the surrounding villages into service—including Yuva, a sturdy young farmboy with a strong back but no experience in battle, and only a battered old helm and wooden shield to protect him.
Master of science fiction Tsutomu Nihei (Blame!, Knights of Sidonia) turns his unique storytelling voice and architectural eye to fantasy for the first time, offering a dark, gritty tale of swords and sorcery, bravery and adventure, great heroes and ultimate evil.