King Genma, the Maoh King, rules a post-apocalyptic Earth where his Genma tribe subjugates humanity. His regime enforces control over enslaved human populations using mutant armies: intelligent simian soldiers, cyclopes, vampires, and werewolves. Believing offspring conceived with human women possessing latent powers would yield heirs with extraordinary abilities, he systematically abducts and impregnates Hito women. One victim, Non, offers herself in exchange for her village's safety, bearing him twin sons, Loof and Jin. These hybrid children inherit significant psychic abilities and physical traits marking their lineage.

The Maoh King separates the twins at birth. He takes Loof—initially exhibiting more Genma-like traits—to raise as a prince within the Genma hierarchy. Jin, perceived as more human, remains with Non but faces persecution from humans and Genma forces. The king shows no paternal affection, viewing his children solely as tools to perpetuate his dominion. His consort, Queen Parome, resents his prolific impregnation of human women, her jealousy fueling increasing instability. Despite her loyalty, the Maoh King dismisses her potential to bear a worthy heir, deepening her resentment.

After Loof unexpectedly transforms into a human form, the Maoh King exiles him as a failure. Both Loof and Jin eventually unite against their father, seeking vengeance for their mother's suffering and death. During their confrontation, the Maoh King reveals his broader motivation: he orchestrated the hybrid progeny and perpetual war out of sheer boredom. He forcibly sends the twins through a time portal to the era of the Genma invasion's beginning, intending them to become pawns in rewriting history. This plan backfires when Parome, in a final act of betrayal, impales him with a sword during the twins' assault, resulting in their mutual destruction.

His influence extends beyond death. The Great Genma King, later revealed as Dar, is the ultimate architect behind the Genma invasion millions of years prior. This entity manipulates events across timelines, including the Maoh King's reign on Earth, to propagate Genma dominance. Dar’s scheme involves using Maoh King’s descendants—particularly Ran’s unborn child, fathered by the human bandit Dan—as vessels for his reincarnation. Though weakened after a battle with Loof and Jin in the past, Dar’s role as a galactic conqueror underscores the Maoh King’s position as a subordinate instrument in a larger cosmic tyranny.