Saitama (サイタマ) is the titular One-Punch Man and the most powerful being in the series — capable of ending any fight, against any opponent, with a single punch. That power comes at a cost: because nothing has ever come close to challenging him, Saitama has lost the ability to feel excitement, fear, or real satisfaction from combat, and much of the story is built around his quiet, ongoing search for an opponent who can finally give him a real fight.
He wasn't always this way. Saitama started out as an ordinary, unemployed salaryman until a chance encounter convinced him to become a hero purely for fun — no tragic backstory, no ulterior motive, just a decision to start helping people. Three years of brutal, self-designed training built him into something that could shatter that kind of power ceiling, though even he can't fully explain how it worked. He eventually registered with the Hero Association after realizing that operating unofficially meant nobody — the public included — recognized what he was actually doing, and now holds the hero name Caped Baldy at A-Class Rank 39, defending Z-City against Mysterious Beings and whatever else shows up.
Off the clock, Saitama is almost aggressively unremarkable — he shops the bargain sales, plays video games, and routinely fails to remember the names or faces of heroes he's fought alongside more than once (Genos, his live-in disciple, is one of the few people he consistently gets right). That same flatness defines how he fights: he lets opponents monologue, power up, and throw everything they have at him, then ends it in a single motion — which is exactly what makes his battles read as anticlimactic rather than triumphant. For Saitama, winning was never actually in question.
Saitama is a human male of average height with a lean but deceptively muscular build. His most prominent feature is his completely bald, shining head; he has dark eyes and a simple, often “derpy” expression that sharpens into an intense, detailed look during serious moments.
His hero costume is a plain yellow jumpsuit with a short high collar, a black belt with a gold circular buckle, red gloves, red boots, and a long white cape fastened by two black circular buttons. Off-duty, he favors hoodies or t-shirts with puns like “OPPAI” or “NIKU.”
Three years before the story, Saitama had a full head of thick black hair — he lost it partway through his training regimen, around the same time his strength began to spike.
Deadpan and Detached
Saitama is indifferent and unimpressed by hero tropes or villain monologues, suffering from a profound ennui brought on by having no real challenge left.
Simple Motivations
He became a hero “for fun,” and these days is driven by decidedly mundane concerns — supermarket bargain days, rent, and video games with King.
A Firm, Simple Moral Compass
He believes a hero’s duty is to protect people regardless of rank or fame, once telling Fubuki that hero factions are pointless if they don’t actually save lives.
Forgetful, and Quietly Worried
He frequently forgets the names of villains he’s beaten or details from briefings, and privately worries that he can no longer grow as a person.
Saitama was an ordinary, unemployed job-hunter in City Z. Three years before the main story, he encountered the monster Crabrante hunting a boy with a cleft chin; despite being a normal human, he fought the monster off with his necktie to save the child, reawakening his childhood dream of becoming a hero.
To chase that dream he committed to a daily regimen for three years: 100 push-ups, 100 sit-ups, 100 squats, and a 10km run, without air conditioning. About a year and a half in, his hair began falling out as his strength surged. According to Dr. Genus, Saitama’s sheer obsession allowed him to break his “Limiter” — a natural biological growth cap — granting him what is effectively infinite potential.
House of Evolution Arc
Saitama defeats Dr. Genus’s strike force and kills their ultimate creation, Carnage Kabuto — distracted the whole time by worry over missing a Saturday sale.
Hero Exam & Early Career
He joins the Hero Association, shattering every physical record but scoring poorly on the written test, landing him in Class C. He later destroys a meteor threatening City Z (and gets blamed for the debris damage), then kills the Deep Sea King in City J while letting the public believe other heroes had already worn the monster down.
Alien Invasion Arc
Saitama boards the Dark Matter Thieves’ ship and duels their leader, Lord Boros, eventually splitting the sky with a Serious Punch to kill him.
King Arc
He discovers that S-Class hero King is a “fraud” who has been unintentionally credited with Saitama’s own kills for years — the two become close friends and gaming rivals regardless.
Monster Association War
Saitama defeats the Monster King Orochi underground, then faces a fully monsterized, “Cosmic Fear” Garou in a battle that escalates all the way to Jupiter’s moon. He masters a time-reversal technique from Garou and uses it to prevent the deaths of the other heroes, before helping steer Garou toward redemption rather than killing him.
Neo Heroes Era
Promoted to Class A, Saitama moves into Hero Association HQ. Neo Heroes scouts approach him about becoming an executive; he shows little interest, preferring his current lifestyle. He later has a large-scale skirmish with Tatsumaki, focusing on restraining her to limit collateral damage until she wears herself out.
Immeasurable Strength & Absolute Speed
Saitama can reportedly shatter planets, part the atmosphere, and move fast enough to leave dozens of afterimages, crossing Moon-to-Earth distance in seconds.
Infinite Durability
He has taken no damage from nuclear-fission-level blasts or being kicked through buildings.
Technique Series
His moves are self-categorized into a “Normal Series” (e.g. Consecutive Normal Punches) and a “Serious Series” (Serious Punch, Serious Sneeze, Serious Table Flip, Serious Sideways Jumps) — the Serious moves surface when he’s slightly more invested, though still nowhere near his full potential.
Zero-Punch / Reverse Causality
Learned during the fight with Cosmic Fear Garou: a technique that lands a blow by reversing time so the strike occurs before it’s even thrown.
No stated limitations on his power appear in this data — he is not shown being seriously challenged physically by any opponent.
vs. Boros — Ch. 34–37
Boros unleashed everything, including the Collapsing Star Roaring Cannon. Saitama split it with a Serious Punch and ended him — the first time he acknowledged an opponent as “strong” enough to use a real technique.
vs. Orochi — Ch. 108/112
The Monster King tried to sacrifice him to the Earth's core. A Serious Squirt Gun and a normal punch later, it was over.
vs. Garou — Ch. 161–166
Absolute Evil against Absolute Strength, in a fight that spanned the solar system. Garou lost — and found redemption in the process, proof that Saitama's power can bend even causality itself.
Major appearances: Ch. 1–11, 15–18, 21–28, 32–37, 91–100, 108, 161–167, 186.
Minor appearances: Ch. 12–14, 19, 20, 29–31, 38–63, 101–106, 171–185, 201–205.
Mentioned only: Ch. 117, 119, 188.
Genos
His self-proclaimed disciple. Saitama treats him as a roommate and friend, if a somewhat exhausting one given Genos’s long-winded explanations.
King
His closest friend and gaming rival — the only person who can hand Saitama the “defeat” he craves, if only at video games. Saitama is one of the few who knows King’s S-Class reputation is built on credit for Saitama’s own kills.
Bang (Silverfang)
A senior hero Saitama respects, though he routinely turns down Bang’s invitations to join his dojo.
Fubuki (Hellish Blizzard)
A frequent visitor to his home; Saitama regards her faction-building as a nuisance.
Tatsumaki (Terrible Tornado)
Largely antagonistic at first — she dismissed him as an “insect” and “chrome dome” before a city-wide skirmish ended with her begrudgingly admitting he was “tough,” while still refusing to call him a friend.
Garou
Initially dismissed as a “dine-and-dasher,” before their fight escalated to a cosmic scale. Saitama ultimately chose to help him find a new path rather than kill him.
“I’m a hero for fun.”
“In exchange for power... maybe I’ve lost something that is essential to being human?”
“I finally mastered superkiller consecutive punches, but your defense is perfect!” — to King
“20 words or less!”
His name is taken from the Saitama Prefecture in Japan, where creator ONE lived. He was the only hero to score a perfect 50/50 on the Hero Association’s physical fitness test.
He keeps a shrunken Overgrown Rover (nicknamed Pochi) and the one-eyed monster Manako (Oculette) as unofficial pets.
🇯🇵 Japanese Voice Actors
Furukawa, Makoto
🇯🇵 Japanese
🇺🇸 English Voice Actors
Mittelman, Max
🇺🇸 English