Ragnarok

In the late-medieval land of Barnard, between the mountains and sea, the peaceful lifestyle of the people has been shattered by fear. Monsters known as the Dark Ones roam the land, killing indiscriminately. The townsfolk fear to venture out from their homes, and travel from town to town has become a risk to life and limb. To protect the people from this terror, several guilds have sprung up, including the Guild of Assassins and the Guild of Mercenaries. To go out into the world, or travel across the wilderness, hired mercenaries are essential.

One man has built a reputation as an especially fierce monster-killer ‹ a man known as Leroy Schwartz. A former high-ranking member of the Guild of Mercenaries, Leroy has struck out on his own. Many try to hire him for his superior skills, but Leroy has his own agenda. He has a mission to accomplish, a vow to fulfill. This vow is known only to himself, and his one companion: his sentient long-sword Ragnarok.

(Source: ANN)

Ragnarok was published in English as Sword of the Dark Ones by CMX Manga from April 1, 2005 to October 1, 2005.