A manga and anime horror series by Kei Kusunoki. The
story concerns a nameless young man, born of a ogre but with the
form of a human. The normal ogre's horn, rather than being
attached to his body, was a sword, the "onikiri maru", or
"ogre slayer"; he is only known by the name of his sword. He
believes that if he hunts down and kills every last ogre in the
world, that he will become fully human. But ogres can be born
from many things, from fresh corpses or even the crotches of dead
trees. So he travels the world in his seemingly futile quest,
attempting to rid the world of ogres.