Monster King Orochi originated as a human transformed through experiments conducted by Gyoro Gyoro, later exposed as the esper Psykos. These procedures involved monster cannibalism, cell transfusion, and psychological torture, culminating in Orochi becoming the first successful Dragon-level threat creation. Post-transformation, he discovered ancient ruins deep underground featuring a mural depicting a figure resembling him alongside sacrificial offerings. Interpreting accompanying texts, Orochi believed the chamber prophesied his resurrection as a god, contingent on securing a "worthy sacrifice." This conviction drove him to secretly perform sacrificial rituals while maintaining outward obedience to Psykos. Orochi nominally led the Monster Association, though Psykos served as the true strategist. His colossal form featured pink skin, glowing yellow eyes, multiple sets of sharp teeth, horn-like spikes, and snake-skull joints at the knees. A large cape concealed a torso composed of intertwined serpentine dragons, enabling a "released form" metamorphosis where his body unraveled into dragon-headed tendrils capable of stretching, generating claws, and breathing fire. A subsequent "true form" unveiled a centipede-like body with multiple legs after shedding a facial mask. His personality blended stern authority with strategic cunning. He demanded absolute obedience, instantly devouring subordinates like Awakened Cockroach for retreating, yet spared figures such as Do-S when their utility outweighed failures. Typically laconic and compliant with Psykos, Orochi prioritized personal agendas, exemplified by ignoring her distress calls during the Hero Association raid to confront Saitama. He demonstrated analytical intelligence in combat, rapidly copying techniques like Garou's Water Stream Rock Smashing Fist after minimal observation, and selective pragmatism, offering defeated adversaries like Gouketsu a choice between death or alliance. Orochi ranked among the series' most formidable entities. His physical prowess allowed casually overpowering Garou, intercepting self-destruct mechanisms in advanced robotics, and surviving after Saitama obliterated most of his body. Pyrokinetic breath melted stone environments, requiring protective barriers for allies. Additional abilities included electricity generation, elastic limb extension, and creating Monster Cells to transform humans. Metamorphosis enabled size manipulation, reshaping limbs into dragon-head projectiles, and post-destruction regeneration by absorbing other organisms. During the Monster Association arc, Orochi fought Garou under Psykos's direction, using non-lethal force to stimulate the hero's monster transformation. He later confronted Saitama after sensing his unique power and deducing he had defeated executives like Gouketsu and Elder Centipede. Identifying Saitama as the prophesied "worthy sacrifice" for godhood, Orochi attacked but was obliterated by a single punch. Surviving as regenerative biomass, he absorbed nearby monsters and ambushed Psykos, attempting to assimilate her powers. This fusion created Psykos-Orochi, though neither consciousness achieved full dominance. Tatsumaki atomized the merged form, yet residual flesh samples collected by Drive Knight left Orochi's status ambiguous. Orochi's motives evolved: initial obedience to Psykos masked a quest for deification through sacrifice, shifting to vengeance against Saitama post-regeneration. The mural's prophecy regarding a "god" awakening via sacrifice remained unresolved, with implications that Orochi himself might have been the intended sacrificial offering rather than the beneficiary.