Macadamian Ogre, alias MAO, was a professional wrestler on Earth locked in a losing streak against his rival, Genzo Shibata (Animal Mask). Their climactic World Championship bout ended abruptly when Animal Mask vanished mid-fight, convincing MAO his opponent fled to avoid defeat. This plunged MAO into depression; he refused all further matches, waiting solely for a rematch while managing his zoophobia (fear of cute animals) through activities like stitching.

Summoned to a fantasy world by the vampire princess Joanna, MAO discovered Animal Mask had arrived earlier as humanity's "Hero." Joanna appointed MAO the new Demon King to lead her faction against the humans. This reignited his drive to defeat Animal Mask, launching him on a journey across the new world to find his rival for their long-awaited rematch.

Physically, MAO possesses an athletic build, sharp teeth, dark vine-like hair, and cyan eyes. He typically wears long pants, pink boots, and protective elbow and knee gear. As Demon King, he sometimes adds a black vest adorned with horn-like purple trimmings.

MAO's personality fixates on his obsession with finally defeating Animal Mask, born from repeated losses. Despite this intense rivalry, he harbors no hatred, maintaining a competitive rather than antagonistic view. His zoophobia remains significant, crippling his ability to confront cute animals though not intimidating ones.

His abilities showcase peak human strength and endurance, allowing him to fight Animal Mask evenly. MAO wields extensive proficiency in professional wrestling maneuvers. His zoophobia persists as a key weakness, limiting his effectiveness against certain creatures in this new world.

His journey culminates in a decisive wrestling match against Animal Mask within the fantasy world, resolving their enduring conflict.