King/Synopsis

History
In his childhood, King had won several video game tournaments. At some point within the past 1.5 - 3 years, King was attacked by the Octopus Claw Man, receiving his characteristic three scars as a result, but is saved by Saitama, who was training to be a hero at the time.

Saitama would go on to save his life five more times by destroying the monsters in his vicinity, Vaccine Man among them, but King would always, and unintentionally, get the credit since he fell into the remains of Vaccine Man’s blood on the floor by accident. The Hero Association, capitalizing on the reputation of his strength, made him an S-Class hero without having to take the hero exam and King would be known as "the strongest man on earth". This would continue and King would be paid for the deeds that he had not done.

Saitama Introduction Arc
He picks up a game he dropped and is mistaken as the one who killed Vaccine Man.

Alien Conquerors Arc
King appears at the S-Class Hero Association meeting. During the attack of the Dark Matter Thieves, King is standing on top of the Hero Association's headquarters along with Genos, Child Emperor, Tatsumaki and Superalloy Darkshine after having crawled up from a hole that Saitama made. While Child Emperor considers how to deal with the Dark Matter Thieves' mother ship, Superalloy Darkshine takes the initiative to ask King for his opinion on the matter. King's engine activates as he simply replies that there's nothing he can do. In response to their questioning looks, he follows up with stating that the target is too far up in the sky for him to attack, and suggests that they should use the opportunity to call Metal Knight instead. Tatsumaki promptly protests by calling King pathetic for not taking initiative against the enemy, who has already laid waste to A-City, but is still heeded as the world's strongest man. Superalloy Darkshine warns Tatsumaki that King might kill her if she angers him.

King Arc
During a walk in his home city M-City, he involuntarily encounters Tongue Stretcher and his perverse assault on pedestrian women. Whilst silently deploring his status as a hero, he stands next to the mysterious being as his cover is blown off by the wind, revealing his fearsome malicious stare along with his King Engine. This merely startles Tongue Stretcher at first, but shortly startles him into despair as he is overwhelmed by the menacing aura. A bystander quickly recognizes King's identity and shouts out his name, reminding Tongue Stretcher of who he is up against. The bystanders cheer King on as the monster cowers down on his knees and begs for forgiveness. The surrounding citizens shout various positive and negative remarks at King and the monster, who is supposedly having a seizure from excessive crying, respectively. King is soon crowded by fans who shower him with questions, admiration, love confessions and the likes. Someone asks if he came from sensing a monster, but King says that he was just shopping. Someone else comments on King's face, claiming that he was pissed, but King mildly objects. He picks up his cap to brush it off and declares that he was in a hurry and needed some space. The crowd gets alarmed and fusses about giving King a path and apologizes for being intrusive. King carries on with his business and stops by a TV-game retail store to buy a dating sim called Doki Doki Sisters. Relieved to have finally bought it, King makes his way home while relishing the excitement of having a newly bought game with him. However, it doesn't take long until he hears the screams of another "monster" showing up. Behind him lands a giant robot who introduces itself as G4; a "machine god" created by The Organization. G4 remarks King's status as the world's strongest human and thus that it has come to kill him. Someone recognizes King and shouts out his name. The fleeing pedestrians stop and form a cheering crowd behind him, convinced that everything will be fine now that King is here. Questioning the robots origin, King warns it of his title as the Rank 7 S-Class hero "King; the strongest man on Earth". G4 pays no heed to his rebuttal and swings down a giant sword at King, knocking his hat off and restates that it has come to kill him. The robot follows up by informing King that this is for a battle AI performance test, to which King has no idea what it is talking about. He goes along by saying that he must go to the bathroom first in order to fight at full strength, reasoning that it couldn't get sufficient data if King was holding it in. This convinces G4 and gives King a ten-minute bathroom break. However, G4 warns that if he does not come back within that time, ten people will die each minute and that if he runs away, the town will be no more. King enters the bathroom and drops his game on the floor. His breathing quickly accelerates to hyperventilation as he realizes that his name and reputation have no effect on the robot who came to fight him. Hearing of the impending destruction, which, unbeknownst to him is actually Genos facing the robot, King attempts to formulate a plan for a moment but fails to come up with one and runs from the bathroom with his game, silently apologizing to the masses he has abandoned.

Returning to his apartment, King starts up his game system to relieve himself of the stress and debates about what name to use. Saitama suggests that he use his hero name and only then does King notices him. Saitama reveals that he entered through the open window, though King notes that he lives on the 22nd floor of his complex. King attempts to frighten him off by taking advantage of his reputation as an S-Class hero, but Saitama is unfazed, merely expressing surprise at the fact that King bought a dating sim. A horrified King tries to cover it up by claiming that he was aiming to buy an action game but mistook the title for one of an action game. Saitama then suggests that they play one involving robot battles instead, believing that King ran away from the robot because he was bored. King reluctantly plays the robot game instead, inwardly fuming about Saitama's intrusive presence and his interruption of his peace. Saitama then asks him about fleeing from G4, noting that Genos is fighting in his place instead, causing King to spit out his juice in shock and his heartbeat to quicken in an attempt to find a suitable answer to Saitama's questions, unaware that Saitama believed that he had found a kindred spirit in him. Shortly after, a Demon-level Giant Crow spies Saitama's bald head and lunges right into his apartment, wrecking the area. Saitama, believing that the Giant Crow headed for King instead, suggests that King had no choice but to fight it back. Unwilling to die from Saitama provoking the bird, King shuts his eyes and shouts the truth behind his alleged heroism.

Hearing the ensuing conflict, King initially believes that Saitama was eaten by the Giant Crow, but opens his eyes and realizes that Saitama had defeated it. Saitama then realizes that King's alleged fight history and strength were all lies, noting that King had urinated in his pants from the bird's attempted attack. Saitama asks if he is okay, at which point King realizes that Saitama was the hero who saved him in his previous encounters with mysterious beings.

A tearful King apologizes for unfairly taking the credit that should have been Saitama's, but Saitama brushes it off, instead asking King whether it was fun pretending to be a hero while being scared, to which King replies that it was not, and whether King would continue or give up hero work, to which King replies that he does not have the guts to decide. Saitama replies that King just has to become stronger and tells King that he might come over to play video games with him and leaves.

The Blizzard Group Arc
King visits Saitama's place in order to retrieve his portable video game console. Saitama confessed to erasing the data, which King accepted and didn't mind, but noted that the button was broken. Fubuki was surprised with King's entrance, wondering how S-Class heroes are attracted to Saitama.

Monster Raid Arc
King is called by the Hero Association to help protect the Association's sponsor, Narinki and his son. King replies by saying that he's busy defeating a monster, specifically a monster in a video game.

Super Fight Arc
While playing a video game, the power goes out and he notices the sirens.

King meets Saitama in a deserted street and tells Saitama he was going to buy manga when he noticed that Saitama looked sad. King and Saitama share a deep conversation about being a hero and King gives Saitama some insightful advice to him, though he copied it from a manga. King then invites Saitama to play video games and promises to play with only two fingers, which piques the latter's interest. King is then spotted by Garou, who was injured during his fight with Watchdog Man. Just as Garou is about to hit King, Saitama kicks Garou into a wall, saving King.

Monster Association Arc
He later plays against Saitama and defeats him, despite having a two-finger handicap. King then proceeds to beat Saitama many more times in video games.

When King reveals to Saitama the emergency transmitter and the request for help, Saitama begins to worry for his student's well-being. He and Saitama decide to go to help to the location of the help signal. When they arrive at the scene, King lures Elder Centipede to his position by pretending that he brought Blast along with him based on the classified information he got from the Hero Association and proceeds to taunt the monster. As the monster rushes towards King, King tells Saitama to finish off Elder Centipede in one clean shot to avoid its escape and to minimize collateral damage. When Elder Centipede rushes at him, he panics, thinking Saitama had missed the window and left him for dead, and screams for Saitama as he is about to get hit. After Saitama destroys the monster with a serious punch, he notices that Saitama is a lot more refreshed and not as stressed looking, like he was a few minutes ago while Saitama states that he just feels relaxed all of a sudden and that he was still stressed after losing to King too many times in video games. King states that he was just trying to teach Saitama that his way of fighting was too predictable.

As Genos asks Saitama what he still lacks to defeat powerful monsters, Saitama simply states "power", making King feel uneasy as Genos writes Saitama's "words of wisdom" in his notebook while stating in his mind that Genos shouldn't use someone like Saitama as reference for power.

King is playing video games with Saitama at his apartment with Bang and Bomb resting and Genos doing repairs. Fubuki arrives and tries to rally them into action. She asks King if he could help but he replies that he has something planned. Night has fallen and at approximately 20:07, King is playing video games with Genos observing closely. King worries over Saitama before he returns as Genos detects high-speed movement and sends King to deal with the situation. King invites the mystery person in and he reveals himself to be Dr. Kuseno much to King's relief. King and everyone at Saitama's apartment have hotpot. When everyone is picking their food from the hotpot, King is accidentally knocked out. When he comes to in the morning, Saitama asks him to take out the garbage on his way back to his apartment, which he does. When he goes back home, he encounters two Hero Association workers, who believe based on the stains on his clothes and that he said he was in Z-City, that he was battling monsters all night.

King is escorted to the Hero Association HQ. There, he is further escorted to the S-Class meeting and ends the argument between Sweet Mask, Flashy Flash, Zombieman and Tatsumaki, due to them mistaking the stains King's clothes as blood from all-night fighting with monsters in Z-City. King is informed of the rescue operation and tries to hide in the same room that Bang and Bomb were waiting in. He shares his information with them and they plan to join the operation alongside Genos and Saitama using King's route. They decide to meet at Saitama's apartment. When King arrives, Fubuki, Genos, Bang, and Bomb are there. Saitama is missing and they plan for Genos to wait for him while the rest heads out much to King's reluctance.

King ends up alone in the Monster Association HQ and attempts to calm himself down. He comes across what appears to be Waganma and, knowing he can't protect the boy, he tells him to go to another hero, explaining he can't expect anything from King and that no matter what, it would only turn into despair. However, it turns out to be a monster disguised as Waganma, believing that King had figured out his disguise, which causes the monster to panic to the point of death, turning into a pile of goo. As King continues to wander through the headquarters, he encounters Tareo by chance. The child is relieved to see the hero, and runs toward him with tears in his eyes. However, thinking he is another monster in disguise, King orders him not to move, telling him to drop the act and reveal his true form. As it turns out, there was an invisible monster preparing to attack both of them, and assuming King was referring to it, immediately flees. The two walk up a long flight of stairs and find an elevator, much to King's relief, they get on unaware that they are being tracked by a piece of Orochi but just as he is about to absorb them, the shockwave from Saitama’s punch in another part of the base causes some rocks from the walls to drop into the bucket of the water elevator, shooting both King and Tareo up at an alarming rate and narrowly evading being devoured by Orochi.

When Tatsumaki lifts the Monster Association base up, the elevator rapidly drops, spilling King and Tareo out onto the surface. They meet up with Genos, who asks King what he's doing and where Saitama is. King says he doesn't know, but soon realizes that he, Genos, and Tareo are surrounded by Orochi's roots. Genos promptly incinerates the goo-like substance, and the three of them suddenly see Psykos's fused form burst out of the uprooted Monster Association base. King suggests to Genos that they should leave the fighting to Tatsumaki and is later seen retreating from the battle with Tareo.

While escaping the battle in Z City, King and Tareo encounter a physical anomaly, with the space in front of them appearing distorted. They decide to go around it, but the distortion turns out to be quantum stealth shield hiding a tank. They run into Metal Bat, who is heading towards the battle, as well as Pineapple, Mohican, Food Battler Futoshi, and Waganma, who were inside the tank. Sekingar steps out of the tank to join the heroes and children, congratulating King on a job well done.

He goes on to state that no confirmation was given on the status of the cadres, and thus King and Metal Bat will head back into battle to back up the rest of the S Class. Tareo requests King to help the man who helped him, to which King responds that he will, unaware that the person in question is in fact the Human Monster Garou. Metal Bat fashions a slingshot using spare parts from a broken-down car, and Sekingar lasers the rope, sending King and Metal Bat flying towards the battle. They land in a bush after being caught by a Z City batting cage net, and Metal Bat beckons King to join the battle with him. At some point, Metal Bat decides to separate from him and tell him to take a side to keep any runners from getting away, much to his confusion. Later, when Tatsumaki and Genos are being surrounded by countless clones of Black Sperm and are in critical state, King appears in front of several of Monster Association executive members. He looks composed and confident but within his mind, he is extremely terrified and he regrets trying to save Genos. He is distraught, realizing all the monsters in front of him are powerful enough that they are not afraid to face him. King is still waiting and not making his move, prompting Black Sperm, Golden Sperm and Homeless Emperor to wonder what he is up to. Before Homeless Emperor can test King by trying to attack him with his massive energy sphere, King asks him what if he touched his energy sphere, which he answers that the hero would be vaporized. Homeless Emperor proceeds to try to make the first move, but just as he is about to attack, King advises him that he should pay attention to the loose rocks under his feet in order not to fall. Homeless Emperor, however, mistakenly takes that as a warning that King would be able to instantly dodge his attack and kill him. Despite being stressed, Homeless Emperor still declares he will show everybody the "real" King, which causes the him to incorrectly assume Homeless Emperor has discovered the fact that he is actually just a normal human. Within his mind, King is frightened but still speaks "just an ordinary human" to Homeless Emperor and unnoticeably apologizes him. After hearing King, Homeless Emperor panics and believes the hero has figured out his weakness. Fearing that he would be in deep trouble if monsters such as Black Sperm too discovered his fragile human body without his light powers, Homeless Emperor tries to quickly attack King to prevent him from anymore talking. However; before he could launch his energy sphere, Zombieman suddenly emerges behind Homeless Emperor and grabs his neck, knocking him to the ground and restraining him.

Psychic Sisters Arc
He comes to Saitama's new place to welcome him there but he isn't around. He defends him saying that Metal Knight's robots self-destructed.

Neo Heroes Introduction Arc
After the events of the last arc, Atomic Samurai's attention is brought to King after Bang announced his withdrawal from the Hero Association in order to run his dojo with his brother. King is found eating at a rotation-sushi restaurant by Atomic Samurai and his apprentices, dressed in his normal street attire. King is caught in the sight of Atomic Samurai, who decides to challenge "The World's Strongest Man". King is taken aback by this challenge and starts to choke on his food, which is misconstrued as laughter by Atomic Samurai, leading to Atomic Samurai taking note of boldness. King raises his chopsticks as his choking subsides, making Atomic Samurai believe that King only plans on using the chopsticks to defeat him, and in response, he performs an Atomic Slash on a nearby apple, causing King to panic. King then heads outside, too nervous to say anything to get himself out of the situation, and just stands still, shaking wildly at his impending doom. Atomic Samurai's disciples mistake his fear for bloodlust, and his lack of form as layers upon layers of feints, and Atomic Samurai simply observes but grows tired of the stand-off. When Atomic Samurai finally moves in to attack, King raises his voice, telling him that it's time to stop. King proceeds to bluff his way through to stop the fight, arguing about a nonsensical phenomenon, which he dubs the "Dolzenabring Reaction", which would lead to far too many casualties for such a fight to be an act of heroes. Atomic Samurai is too confused to understand how ridiculous King's claims are, and resigns himself from the fight, on the condition that he tests King's ability to cut an apple using his blade. Atomic Samurai claims that he can learn much about a man through the way he cuts an apple, and states that his disciples all performed a similar test. King has no objections but finds that he lacks the strength to unsheathe the blade.

After a few minutes of holding his form, King drops the sword and walks away, believing that any further bluffs would lead to disaster, hoping that he's not followed. Atomic Samurai breaks into a cold sweat, completely misunderstanding what just occurred. While King never actually swung the sword, Atomic Samurai believes, due to King's renown, that King managed to swing the blade so fast and so precisely that he managed to pass between the cells of the apple, declaring "This apple... it hasn't even noticed that it's been cut." Atomic Samurai laughs about the fact that he had the gall to challenge King, when he himself has so much to learn. Atomic Samurai declares to his disciples that he's restarting his training from the top, and asks if they are still willing to follow him. While King continues walking away, they all agree.

After avoiding a battle with Atomic Samurai and hearing that Bang quit the Hero Association, King goes to Bang's dojo. Charanko is amazed that King came to the dojo, while Bang reminds King that he no longer works for the Hero Association. King explains to the martial artist that since Bang quit being a hero, he became more willing to admit the secret of his weakness. Then, in a surprise to Bang, King asks the martial artist to train him and make him stronger. Unfortunately, Bang is not immune to the false image of King and assumes that King bluffs because of the pressure from people who worships him and instead recommends his brother Bomb to train King.

Eventually, King is told to seek training at the Final Training Ground. Here, King stumbled upon Garou deep in meditation under a waterfall. Startled, King hid himself, but Garou had already sensed his presence and opened his eyes.

Neo Heroes Uprising Arc
Later on, King was seen vigorously doing pushups as part of his assumed training, mimicking Saitama's training.