The Deep Sea King, also known simply as the Sea King, serves as the primary antagonist of the Sea Monster Arc in One Punch Man. As the ruler of the Seafolk, he leads their invasion of the surface world with the goal of wiping out humanity and conquering the land. He views himself as the rightful dominant species, believing that because life originated in the ocean—and he reigns over it—he stands at the top of the natural hierarchy and is entitled to claim the surface as his own.
Appearance[]
In his dry form, the Deep Sea King appeared as the most human-like among the Seafolk. He was tall and muscular, with dark green skin covering his arms, legs, and back, while his chest and abdomen were a lighter tone. His face featured sharp eyes, prominent fangs, and fins extending from both sides of his head. Instead of eyebrows, he had small pink oval markings. His outfit was flamboyant—consisting of a red speedo, a regal crown, and a large fur-lined cape held together by a fish-shaped clasp. Notably, he had heart-shaped nipples.
Hydrated and true form
When hydrated, the Deep Sea King’s appearance shifted dramatically. He became significantly larger and more menacing, growing a long dorsal fin down his back, as well as additional fins on his forearms and shoulders. The fins on his face also expanded in size. His skin turned a bright aquamarine, and his once humanoid face took on a monstrous and intimidating look.
Personality[]
The Deep Sea King is arrogant, ruthless, and driven by an intense sense of superiority. As ruler of the Seafolk, he sees himself as the ultimate lifeform, believing that since all life originated in the ocean, sea creatures—and by extension, he—are the rightful rulers of the Earth. This belief fuels his desire to conquer the surface and exterminate humanity. He takes great pleasure in asserting his dominance over weaker opponents and is both sadistic and theatrical in battle. Despite his cruelty, he craves recognition and is easily angered when someone stands up to him or refuses to acknowledge his strength.
Powers and Abilities[]
Superhuman Strength: The Deep Sea King possesses immense physical power, effortlessly overpowering heroes and crushing his enemies with sheer brute force. His punches and strikes are powerful enough to send opponents flying and cause large-scale destruction.
Enhanced Speed and Reflexes: Despite his bulky frame, he is extremely fast, capable of dodging attacks and closing the distance between himself and his enemies in an instant. His agility allows him to dominate battles against most heroes.
Regeneration and Durability: His body is highly resistant to damage, allowing him to withstand powerful attacks without serious harm. He also has a strong healing factor, capable of recovering from injuries at a rapid rate, which makes him even harder to defeat.
Hydration Transformation: When exposed to water, the Deep Sea King undergoes a dramatic transformation, growing significantly larger and stronger. In this hydrated state, his power, speed, and durability increase exponentially, making him an even greater threat.
Acidic Spit: He can produce and spit a highly corrosive liquid that burns through flesh and melts materials on contact, making it a lethal ranged attack.
Combat Intelligence: Though arrogant, the Deep Sea King is not just a brute—he is an experienced and skilled fighter. His battle against Puri-Puri Prisoner demonstrated his adaptability and combat expertise. He was able to read his opponent's attacks, counter effectively, and take advantage of openings with precise, devastating strikes. Unlike some kaiju-like enemies, he doesn't just rely on raw power but fights strategically, using speed, technique, and intimidation to dominate his opponents.
Story[]
The Deep Sea King makes his entrance after the rest of the Seafolk are swiftly eliminated by A-Class hero Stinger. Appearing suddenly, he knocks Stinger out with a single devastating punch. Witnesses to the scene, Inazuma Max and Jet Nice Guy, try to take him on but are quickly overwhelmed—none of their attacks leave even a scratch on him.
Shortly after, the S-Class hero Puri-Puri Prisoner arrives on the scene, having broken out of prison alongside the ninja Sonic. Puri-Puri clashes with the Sea King in close combat, but it’s clear he’s outmatched. In response, he activates his Angel Mode, unleashing a flurry of punches. However, the barrage barely fazes the Sea King, who counters with a brutal combo of his own, leaving Puri-Puri Prisoner defeated. Sonic then steps in, confident in his speed. He dodges every one of the Sea King's strikes with ease—until rain begins to fall. Rehydrated by the rain, the Sea King transforms into his true form, growing larger, more muscular, and significantly stronger. Realizing he can’t inflict any real damage, Sonic retreats.
The Sea King then targets a civilian shelter, breaking through the dome’s roof. C and B-Class heroes stationed there attempt to protect the people, but they are quickly taken down. Genos soon arrives and engages the monster, managing to damage him, but loses an arm when he drops his guard. Ultimately, Genos is defeated after shielding a girl from the Sea King's corrosive spit. As Genos lies incapacitated, the C-Class hero Mumen Rider (License-less Rider) intervenes. Despite knowing he doesn’t stand a chance, he bravely confronts the Sea King and is easily overpowered. However, his courage and persistence buy just enough time for Saitama to arrive. The Sea King tries to punch Saitama, but the attack does nothing. After arrogantly boasting about his power, he launches another strike—only to be obliterated by a single punch from Saitama, ending the threat instantly.