Ogre Slayer.

For decades, a strange man has wandered across Japan, known solely by the name of the sword he carries—Onikirimaru. Despite his human appearance, he is an ogre who has sworn to eliminate the rest of his kind, hoping to one day become fully human. As he walks this bloody path, he witnesses innumerable human tragedies and knows that he is the only one standing between the ogres and the total destruction of humanity.