Born from an ogre mother, a child emerges with a human appearance but wields a mystical sword known as 'Onigirimaru,' the Ogre Slayer. Nameless but recognized by his weapon, he embarks on a solitary quest to exterminate his own kind, believing his true humanity will surface only after the ogres' extinction from the human realm. Across the mystical lands of Japan, he persists in his mission of eradicating ogres, a relentless force amidst the ancient folklore.