Orochi, the Monster King, originated as a human whose profound bitterness and alienation led to a loss of humanity. Captured by the esper Psykos operating through Gyoro Gyoro, he endured extensive experimentation involving psychological torture, cell transfusions, and forced monster cannibalism. This transformed him into a Dragon-level or higher threat, marking Psykos's first successful creation exceeding previous limits. Orochi gained immense power, establishing leadership over the Monster Association alongside Psykos, though their relationship involved complex power dynamics and mutual manipulation. Physically, Orochi appeared as a colossal humanoid with pink skin, glowing yellow eyes, and multi-rowed teeth. Serpentine elements defined his form, including snake-like shoulders, wrists, fingers, and skull-like knees, often concealed by a large cape. Combat revealed his true composition: intertwined dragon-like tendrils enabling extensive shapeshifting. Against Garou, he unraveled into a "released form" of writhing dragons and claws. Facing Saitama, he adopted a phoenix-inspired battle state with fiery embellishments and avian-like legs. After near-total bodily destruction by Saitama, his remnants manifested as a grotesque biomass capable of absorbing nearby monsters to regenerate. Personality-wise, Orochi exhibited sternness, strategic intelligence, and minimal tolerance for failure, exemplified by swiftly executing Awakened Cockroach. He demonstrated pragmatism, sparing useful monsters like Do-S despite shortcomings. Selective curiosity led him to offer powerful humans like Gouketsu transformation instead of death. Outwardly obedient to Psykos, he concealed his own agenda: discovering ancient ruins depicting a mural resembling him, which he interpreted as a prophecy requiring a "worthy sacrifice" to ascend to godhood. This drove him to feign loyalty while secretly conducting sacrifices within the ruins. Uniquely, Orochi acknowledged Saitama's strength immediately upon sensing him, prioritizing him as a potential sacrifice over aiding Psykos during the Hero Association's raid. His abilities positioned him beyond typical Dragon-level threats. He possessed immense physical strength, speed, and durability, effortlessly destroying advanced drones and overpowering martial artists like Garou and Gouketsu. Metamorphosis allowed limb elongation, tendril generation, and horn manipulation for rapid, heavy strikes. Elemental powers included fire breath and lightning projection, with environmental effects like melting stone. Consuming other monsters enabled continuous growth in size and power. After Saitama reduced him to near annihilation, Orochi's biomass retained consciousness and regenerative capabilities, forcibly merging with Psykos to form a shared mutated entity. This fusion resulted in conflicting consciousnesses, with Orochi intermittently reasserting control to pursue vengeance. Orochi's narrative concluded within the Monster Association arc. Following his merger with Psykos, the combined entity was defeated by coordinated S-Class hero efforts, with Tatsumaki delivering the final blow. No verified information exists regarding appearances or developments in films, OVAs, or spin-off media beyond this arc.