|— Saitama introducing himself to Vaccine Man
Saitama (サイタマ, Saitama) is the main protagonist of the series and the titular One-Punch Man. He is the most powerful being to exist in the series. Saitama faces a self-imposed existential crisis, as he is now too powerful to gain any thrill from battle.
Initially just a hero for fun, Saitama later registers to be a professional hero for the Hero Association upon realizing that nobody recognizes him as a hero, and defends his home in Z-City from monsters, villains, and other threats. Under the Hero Association, he is assigned the hero name Caped Baldy (ハゲマント, Hagemanto; Viz: Bald Cape) and is currently B-Class Rank 7.
After the battle against the Monster Association, he is currently ranked 39th in the A-Class.
Saitama is an ordinary-looking bald man with a thin but well-built physique and is of average height and weight. He used to have a full head of short black hair but lost it due to the intensity of his hero training regimen.
Saitama is usually deliberately drawn in a more simplistic style than the other characters, similar to the style of the original webcomic, with an elliptical head and simple facial features. When drawn in a more serious style, Saitama is revealed to have sharp facial features, fearsome eyes, and chiseled musculature. His posture changes as well, with a slack posture and sloping shoulders when lax, and a straightened posture and squared shoulders when serious.
Saitama's hero costume consists of a yellow one-piece jumpsuit with a short zipper at the collar and a black belt with a round golden buckle at its center. He wears red gloves that go 3/4 up his forearms and red boots that nearly reach his knees. His costume is finished off with a white cape, which is fastened to his shoulders with big, round buttons.
Saitama owns several shirts and hoodies with various designs. This includes his:
- Oppai (Boobies) Hoodie
- Oppai (Boobies) T-shirt
- Mentsuyu (Noodle Soup) T-shirt
- Onsen (Hot Bath) T-shirt
- Ke (Hair) Shirt
- Niku 🍖 (Meat 🍖) Jacket
- Umeboshi (Pickled Dry Plum) T-shirt
- Nezumi Sushi (Mouse Sushi) T-shirt
- Munage (Chest Hir) T-shirt
- Shōyu (Soy Sauce) T-shirt
- Shicago Burusu (Chicago Bulls) T-shirt
- 22nd Super Fight T-shirt
|— Saitama to Genos|
Saitama is an indifferent person. Even the mightiest foes pose no challenge to him, so he does not take his hero work seriously, goes through everything with little to no effort, and yearns for an opponent that can provide him with a challenge. The lack of worthy opponents has led him to suffer from a self-imposed existential crisis, and he claims that his ability to feel any and all emotions has dulled considerably. The combination of his attitude, unstoppable power, and "unimpressive" appearance often causes his battles to become anticlimactic. Saitama will usually allow his opponents to rant about their motives and power up into their strongest forms, before obliterating them with a single punch.
A running gag about Saitama is his inability to remember people's faces and names, as seen when he forgot Speed-o'-Sound Sonic's name, or when he could not remember who Tanktop Tiger was. Because of this, he sometimes ends up pronouncing people's names incorrectly, much to their chagrin.
A more recent version of this gag is when he forgot Flashy Flash's name when he asked Saitama to fix the sword he broke.
Saitama is very humble, as he purposefully let the masses turn against him in order for the defeated heroes to be given credit for their efforts against the Deep Sea King, even claiming that they had weakened the monster before his arrival. He did the same for the police station, killing a monster while disguised as a police officer, despite potentially gaining much fame had he revealed who he actually was. He also did not mind that King took credit for all of his achievements.
Another surprising thing about Saitama is that he is very tactful and insightful, being well able to discern situations and character traits from the people and environment around him fairly easily. He was able to pick up a number of hints to Sonic's persona upon their first meeting. When two tank top heroes jealously plotted to ruin him after the meteor event, he remarked that there were irate and self-serving hero types like them. He was even able to discern Fubuki's forced offer of submission or destruction just before his crackdown on how the hero world really works than how it is currently run.
Saitama has been seen to show remorse to his enemies before, particularly ones who can give him a stimulating fight and don't just go down in one hit. One such example of this is Boros, the self-claimed "Dominator of the universe", with whom Saitama sympathized, due to suffering from similar circumstances. Though in the end, even Boros still couldn't draw out Saitama's full power.
Saitama does not actually care if people insult him, and he usually ignores them and says that they need a hobby; the only insult that could get a reaction out of him is anything pertaining to his baldness. He has expressed distaste towards his officially assigned hero name, Caped Baldy. Thus, even after receiving it, he always refers to himself as Saitama. He also shows a measure of concern when it comes to bargains and deals, as seen when he fought Carnage Kabuto, where he was more shocked upon the realization that he was going to miss a bargain sale, rather than his opponent who had undergone a transformation and was beating him around. Despite his general indifference to most things, Saitama was genuinely shocked when he realized that no one actually knew of him despite his achievements, curious as to why he doesn't have any fans. This reaction demonstrates that while he isn't necessarily into hero work for fame, he certainly doesn't object to it. Another running joke is Saitama's jealousy of higher rankings, such as when he grew irritated when Genos listed off all of the comments made by fans about how amazing Genos is in their eyes.
Saitama demonstrates impressive restraint with his power, considering that he is easily capable of splitting the sky or jumping from the Moon to Earth in seconds. He manages to beat nearly all of his opponents with a single punch, though occasionally causes more destruction than necessary. While he has no problem killing monsters, Saitama has yet to be seen killing another human and only ever uses enough strength to knock them out.
Saitama has proven to be a good figure to other people, both heroes and villains alike. His influence made Genos quiet his revenge wishes and start focusing on training to become a good and strong hero. He has also made insecure people like Fubuki and Glasses stand up to their challenges and become better heroes. Saitama also advises King to train and become strong for real, rather than being upset the latter stole credit from his battles.
As Fubuki notes, he "attracts the strong", as many powerful heroes and villains have taken a liking to him, and few even look up to him as a role model to follow.
Aside from being quite a cheapskate due to his financial status, he has a greedy side seen when tried to steal bags of gold from the underground mine inside the Monster Association Headquarters and was visibly upset after accidentally dropping them down to the bottom of an underground ravine.
Abilities and Powers
|— Saitama on his strength|
Saitama is the titular One-Punch Man and the strongest, fastest and most durable character in the series. So far, no enemy has been able to injure him in any way, and almost no enemy has been able to survive a single earnest punch from him. A few enemies have survived punches from him, such as any human he has struck (whom he restrains himself against) and Boros, whom Saitama empathized with and held back against so as to give himself and Boros a satisfying and stimulating fight. Saitama's only power is that his body is far beyond human limits, allowing him to achieve astounding physical feats. His strength is so great that it vastly eclipses even artificial beings designed or bred specifically for superhuman combat, such as mechanical beings or the mutated warriors from the House of Evolution. Since no enemies have posed any real challenge to Saitama yet, the upper bound of his strength is likely even higher than it currently appears. While his power is only limited to heightened human traits (he cannot fly or fire energy blasts), his superhuman abilities more than compensate for the lack of variety in his powers.
The origin of Saitama's immense strength is mysterious and unclear. Although he tells everyone he got his incredible power through mere physical training, no one believes him at all. According to Saitama, after a year and a half of 100 daily push-ups, sit-ups, and squats, plus 10 km daily running, he had achieved some level of superhuman strength. This training was apparently so intense for Saitama that he at times felt he might die, and claims that it is what caused all of his hair to suddenly and eventually fall out. Genos believes that Saitama himself doesn't actually know or understand how he gained his power, and hopes to learn the secret by sparring with and observing him, while Dr. Genus believes that Saitama worked out with said training regimen so hard that he had removed his Limiter. It should be noted that Saitama would complete all parts of the training one after the other without breaks and was battling monsters that appeared during that time, which would have made completing the training more intense than it would normally be expected.
Despite his unbelievable physical prowess, Saitama can be outperformed by people with skills in areas outside fighting, like when he was bested by Bang in a game of Rock, Paper, Scissors or defeated by King in video games, mostly in one-sided matches. Furthermore, he also seems to possess a normal human appetite, as he lost to Genos in a spicy noodle eating contest.
Unparalleled Strength: Saitama possesses seemingly limitless physical strength and is capable of effortlessly defeating powerful monsters and villains with a single, nonchalant punch (although this strength is not limited to punches). Saitama's punch is so powerful that many enemies simply explode when struck. An example of this casual, yet overwhelming offensive power occurs when Saitama launches himself from the top of a building, blasts right through a giant meteor with a punch, lands safely, and just calmly decides to go home. Another instance is when Sonic tries to slice Saitama's head in half with a sword, but Saitama stops the sword by catching it with his teeth, effortlessly shattering the blade with the power of his jaw. When launched from Earth to the moon by a strike from Boros, he used his jumping power to return to Earth in mere moments, causing a huge shock wave and immense tremors on the surface of the moon upon departure, as well as on Boros's ship upon landing. A "normal" punch from him was shown to be very fatal, even to someone as durable as Boros. A single "serious" punch from him was able to counter Boros's strongest attack, Collapsing Star Roaring Cannon, an attack capable of wiping out the entire Earth's surface. Saitama completely negated the attack using his serious punch, while shockwave from the punch was also powerful enough to part clouds on a global scale. Saitama is capable of destroying the Earth if he wanted to. His strength has been stated by numerous characters to defy reason.
- Enhanced Leap: Saitama's inability to fly is somewhat compensated by his immense leg strength, allowing him to leap tremendous heights/distances at high speeds. This can be seen when Saitama smashed his head through the ceiling of a tall gymnasium during the hero tryouts simply by jumping. He was also able to smash a building into its foundation just by leaping off from its roof. His greatest feat in this regard, however, was when he leaped from the surface of the moon and ended up back on Earth in seconds at a specified point, leaving a crater on the moon's surface in the process. He is also able to jump while still in the air, adjusting his angle of ascent or descent thanks to his amazing power.
- Shockwave Generation: As shown in his practice bout with Genos, Saitama can control and direct his power in the form of a massive shock wave that comes from his punches. He uses this to show Genos a glimpse of his true power, but stops it before actually punching Genos, with the shockwave from the attack completely annihilating the mountain behind him.
Unparalleled Speed and Reflexes: Saitama was able to complete a 1500 meter dash in an instant during his hero tryouts. He has proven able to effortlessly keep up with Speed-o'-Sound Sonic, who can move at above hypersonic speeds. Even Genos's computerized targeting systems have difficulty tracking him. Saitama once bit Sonic's sword at such great speed, Sonic didn't even know what happened. Saitama has also shown the ability to run down a building to save a piece of salmon he was having for lunch, and leap back up said building without bystanders noticing he had even done so. His speed is so impressive that he can even outpace the likes of Flashy Flash, easily dodging his sword swings. When kicked to the moon by Boros's attack, Saitama returned to Earth in mere seconds which shows that Saitama can even travel at sub-relativistic speeds. Saitama also easily blocked Geryuganshoop's near lightspeed rocks, the speed of which being like a bad joke to him. Ironically, despite his incredible reflexes and speed, he still has problems squashing a simple mosquito.
- Afterimage Creation: Saitama's speed allows him to create afterimages of himself. He first used this during his training bout with Genos. He was also able to create an infinite amount of afterimages during his fight with Speed-o'-Sound Sonic.
- Immeasurable Dexterity: Saitama is capable of moving any of his limbs at extremely fast speeds without flinching, not stopping until his target is completely obliterated. This is seen when Saitama flawlessly whacks all moles on a Whack-A-Mole machine during the Hero Association exam.
- Immeasurable Agility: Saitama has been shown to be perfect at dodging and able to perform highly acrobatic maneuvers. Saitama's reflexes render him flexible enough to move through the narrowest creeks and dodge attacks at the closest proximity. Saitama is also able to perform parkour, which he can couple with fighting movements, as shown in his flashbacks.
Immense Stamina: Saitama has never been shown to tire out when fighting enemies. Even when unleashing a punch more powerful than a planet-destroying attack, Saitama showed no signs of fatigue. The only time in which Saitama was shown to be panting and out of breath from continuous running, he recovered just seconds later.
Immeasurable Senses: Saitama's senses are far beyond the human norm. He possesses impressively sharp hearing, being able to pick up on various chatter from bystanders a good distance away even while fighting monsters and the like. He can even hear phone transmissions with well enough accuracy to gauge conversation and the contents of its dialogue.
Saitama is also able to see in the dark, as he was able to spot a kid a great distance away during the night. His tracking capability is also astonishing, as he can concentrate on a fast-moving object for a long time and still not lose sight of it, as seen when he was the only person to see where Garou escaped to.
Invulnerability: Saitama can withstand blows from extremely powerful beings such as Carnage Kabuto without suffering a single scratch or feeling any pain. No character has been able to damage, or even physically harm Saitama. When Genos created a huge, spherical blast of flame to kill Mosquito Girl's mosquitoes, Saitama remains standing right next to him completely unharmed, unperturbed and very dirty (though his clothes were burnt). He also survived being kicked to the moon by Boros in his fully powered state, and going from the Earth to the moon and back with no damage from leaving and entering the Earth's atmosphere (only his clothes were slightly burnt). He even survived the harsh conditions of outer space unscathed during his brief time on the moon. It has been shown that, despite the dangers of holding one's breath in space, Saitama can do so with no negative effects on his body.
Saitama also prefers to dodge or block attacks using edged weapons, rather than take them head-on, as he sometimes does with strikes from fists or blunt objects. However, when he does take them dead-on, the object usually breaks or is destroyed, as was the case of Speed O' Sound Sonic's sword. Nyan's superpowered claw scratches, which can cut buildings in half, were also shown to have no effect against Saitama's head.
- Immense Psychic Resistance: Fubuki noted that Saitama is virtually immune to any psychic attacks and very resistant to being manipulated due to his astonishing willpower.
- It is noteworthy to know that his muscles merely "twitched" when Tatsumaki used her psychic powers on him and that she wasn't able to keep Saitama up in the air for more than a few seconds because he was "too heavy". This demonstrates that Saitama is not completely immune to the effects of psychokinesis.
Enhanced Lung Capacity: Although Saitama cannot breathe in space, he has considerable control over his breath. Even in outer space, Saitama manages to hold his breath effortlessly, and he even made a jump back to the Earth from the Moon in seconds with no signs of suffocation.
Vacuum Adaptation: Saitama's body has been shown to survive in the vacuum of space unscathed for at least a brief period of time. Several factors like a lack of atmosphere and increased exposure of radiation are at play here, although Saitama was not affected by any of them.
Temperature Immunity: Saitama is immune to all types of temperature-based attacks. In fact, he is immune to the effects of temperature in general. When Genos created a huge, spherical blast of flame to kill Mosquito Girl's mosquitoes, Saitama remained standing next to him unperturbed and completely unharmed (although his clothes were burnt to a crisp). Saitama was also able to withstand Withered Sprout's freezing attacks, which were capable of incapacitating 1 C-Class hero, 1 B-Class hero and 1 A-Class hero with ease. The attacks were so strong that the A-Class hero Smile Man thought them to be on par with the likes of a Dragon-level monster. He has also been shown to be unaffected by Monster King Orochi's fire-based attacks, which could even melt rocks or solid substances. This ability can be attributed to Saitama refusing to use either the air conditioner or heater during his training.
Pain Suppression: Before gaining his overwhelming power, Saitama was still able to suppress pain. This has been shown on numerous occasions dating all the way back to his days as a middle school student, taking a beating from two upperclassmen and, later, a Wolf-Level monster Piggy Bancon. He then got back up when the bullies could not and chased after the monster for his money. Other similar feats include taking strikes from Crablante and Personification Of A Light Pull Cord during his training as an adult among others.
Expert Hand-to-Hand Combatant: Despite having no formal training, Saitama is a very proficient and adept hand-to-hand combatant. Thanks to many fights with monsters and villains during his training, he's got a lot of fighting experience and developed a good deal of fighting skills. Due to his immeasurable power and boredom, he doesn't usually care about technique and makes use of flawed basic attacks. His combat skills allowed him to defeat many criminals and monsters even before gaining his immeasurable power. His fighting style is, unlike the likes of Garou, Bang, Bomb and Suiryu, quite simple but solid when backed with his immeasurable power. He can easily read, counter and strike moves and techniques from fighters with far more experience and training than him. Even Suiryu, a skilled martial artist, commented on his fighting prowess during their fight, noting that he had real fighting experience. He is also able to skillfully combine his superhuman abilities to overwhelm his opponents and even use the environment around him to his benefit.
He also uses karate chops and grappling moves to take down villains he doesn't want to kill, or just to knock out people who pick on him.
Improvisation: Saitama is very proficient with improvised weapons, such as when he killed his first monster by deftly using his tie to grab the monster's eye and tear out his intestines. He is proficient at improvising in general, whenever he can't solve a fight with a punch or directly can't punch his foe, he always comes with a solution with one way or another and uses very unique moves that are supported by his immeasurable power.
Extremely High Accuracy: Saitama seems to have almost perfect precision since anytime he focuses on a target, he always strikes it. He is able to turn a rock into a deadly projectile that hits its target, as shown when he killed Geryuganshoop. He had no trouble landing directly on Boros's ship from the moon, even though the angle to return to Earth was extremely small, leaving very little room for error.
Normal Series: Saitama's Normal Series consists of techniques in which he puts very little effort into attacking. Even though his attacks are loose in this style, most opponents tend to be finished off easily due to Saitama's tremendous strength and speed.
- Normal Punch: Saitama punches his opponent. Even though Saitama puts very little to no effort in his punch, it is still strong enough to kill almost every opponent, including Dragon-Level threats, blowing apart their bodies, crushing their skulls and bones or even beheading them. When facing humans however, Saitama holds back greatly, only using enough strength to knock them out.
- Consecutive Normal Punches (連続普通のパンチ, Renzoku Futsuu no Panchi): Saitama launches a volley of quick, single-handed punches from his right hand. These blows are powerful enough to blow strong or large body types apart into pieces. Boros was only able to survive this attack using his intense regenerative abilities.
- Two-Handed Consecutive Normal Punches (両手・連続普通のパンチ, Ryōte Renzoku Futsū no Panchi): Saitama launches a volley of quick punches from both hands instead of one.
Serious Series (必殺マジシリーズ, Hissatsu Majishirīzu): In Serious Series, Saitama still attacks without putting in much effort. But Saitama's face looks more serious when he performs Serious Series attacks. Saitama does not actually consider these moves to be anything special.
- Serious Punch: (マジ殴り, Maji Naguri) Saitama throws an extremely powerful punch. The full extent of this attack is unknown, as it has never directly hit an opponent. It was so powerful that it completely negated Boros's Collapsing Star Roaring Cannon, a beam capable of wiping out an entire planet. The shock wave from the punch alone was powerful enough to part the clouds on a global scale, as well as deliver the final fatal blow to Boros. The dying Boros also declared that Saitama's fatal attack on him was not even anywhere near Saitama's true power and that Saitama was still holding back. Saitama also used this move to completely annihilate and disintegrate Elder Centipede, a Dragon-level threat and one of the biggest monsters in the series.
- Serious Side Hops (マジ反復横とび, Maji Hanpukuyokotobi): Saitama rapidly hops from side to side, creating a wall of afterimages. He is able to walk forward while doing so, and the shock waves caused by it were enough to easily render unconsious Speed-o'-Sound Sonic, even with his 10 afterimages. 
- Serious Table Flip (マジちゃぶ台返し, Maji Chabudai-Gaeshi): Saitama digs his fingers into the ground and flips a large amount of ground thousands of meters into the air. He first used this technique against Awakened Garou, and the effect was so great that Garou's sense of gravity and balance was severely warped.
- Serious Headbutt (マジ頭突き, Maji Zudzuki): Saitama headbutts his target. He uses this to counter a punch from Garou and break his arm.
Keen Perception: Saitama is amazingly good at reading people's fears and real motives with just a look, as well as the reason they are how they are. He proves this many times by reading people like Fubuki and Glasses. He also quickly finds out about King's lie but decides to keep it a secret. However, he is usually good at this only when he gets serious.
He is the first to acknowledge Garou's true thoughts and insecurities and realizes that the hero hunter never wanted to become a monster, but rather a hero.
Strong Teeth: In one of his fights with Sonic, the latter attacks him with a sword, which the Caped Baldy replies via biting and destroying said sword with no effort.
Intimidation: While he doesn't seem particularly scary, those who know about his abilities show fear of him. Saitama can emit a "powerful aura", which makes his foes tremble and become pressured, as Sonic and Genos were left amazed and terrified by this feeling. Saitama is able to invoke fear in those he dislikes or who bother him by merely threatening them with simple retorts.
Indomitable Will: Saitama has been shown to possess incredible willpower. It is most evident in the flashback to his hero training regime. Even if he was in great pain, or could barely move, or vomited blood, he continued his training. Through sheer willpower and effort, he removed his natural limiter.
Saitama's willpower is also evident in his fight with Tatsumaki. Saitama's strength of will is directly connected to his psychic resistance. Tatsumaki, the strongest known esper in the universe, was unable to bend Saitama or lift him into space, exclaiming for the latter that he was "too heavy", although this was while she was injured.
Non-Physical Interaction: One example of his strength defying normal logic is when he broke a hole into the Phoenix Space, a spiritual realm that only exists within Phoenix Man's bird costume, by simply knocking on it. This suggests that Saitama can even interact with things that are intangible/non-physical.
- (To the Subterranean People in his dream) "I do not lose. And the surface... is guarded by me!"
- (To Genos, Dr. Genus and Carnage Kabuto) "The true power of us human beings is that we can change ourselves on our own."
- (To Glasses) "Do you honestly think you won't get any stronger for the rest of your life? Instead of sitting around frustrated, it's better to keep moving forward. I'm going now. Today is a special day in case you didn't know. The market is selling veggies at 30% off."
- (To Genos) "Who is gonna fight if all the heroes run away?"
- (To an opposing crowd) "Let me make one thing clear! I'm not working as a hero because I want you morons to admire me! I do it because I want to!"
- (To Boros) "You're still conscious? You really are strong."
- (To King) "Just become strong."
- (To Fubuki after closing in on her) "You won't survive. You don't get what hero means. There are a lot of incredibly strong bad guys in the world. Those who oppose them are called heroes. Even if they are alone. You, who gathers weaker subordinates to feel strong, won't make it. At this rate, you are gonna cry sooner or later. When a monster stronger than you shows up, none of your subordinates will save you. Factions? Newbie crushing? Keeping your ranks? They have nothing to do with anything! Don't look down on heroes, you moron!"
- (To Suiryu) "Those impurities you were talking about have nothing to do with anything. Your name is Suiryu, right? You aren't the only one doing what he wants to do. I'll give you some advice too: If your goal is to have fun, then it would be best if you don't become any stronger than you are now."
- (To Orochi) "Nope! Enough is enough! On the contrary, I have no interest in you whatsoever. What are you getting all excited by yourself now? I'm sorry, but I'm getting tired of hearing these self-introductions. King of these, the ancient weapon of that, the final evolution of something, sealed whatnot, whole universe whatever, so on and so forth. I've fought a ton of dudes like you, what's the big difference? All this stuff about ultimate life form... you'll end up getting one punched anyway. Let's go. But like I said, I'm not expecting anything."
- (Referring to God) "If you got something to say, show your face! I'll still punch you out, though."
- (To Garou) "With that attack, I now know that you are sort of strong. I might even say very strong... But it's not clear."
- (To Garou) "Really, Garou. So you did have an "image of an ideal hero" inside of you. I see now. I now understand what you wanted to do. Even though you said you wanted to be a "monster of absolute evil"... What you really wanted to be was a hero. You compromised and decided to be a monster. To bring about world peace, you took the easy route, thinking a monster's job was quicker and easier than a hero's. A monster role is simpler, after all, all you had to do was defeat heroes. It's perfect for someone with no confidence like you. BUT YOU CAN NEVER DEFEAT ME. Peace made by ruling the world with fear can't succeed as long as you can't defeat me. It will never work. It's absolutely impossible for you. Your compromised monster hobby! VS my serious hero hobby! Even if that's all I had, I still wouldn't lose! It was a mistake to lower the hurdle right before the goal. A half-assed objective can't succeed. But what about "next time?" What will you do next?"
- (To Sweet Mask) "Dude, no... I'm not gonna let this little brawl turn into a murder. This matter's already been settled."
- (To Sweet Mask) "Would an ideal hero care about the attention of others? Compared to that, how do you view yourself? Isn't how you view yourself more important? After all, we're human."
- "You should go and become your own ideal hero."
- Saitama's hero profile number is 03402.
- Saitama is ranked 1st in the character popularity poll.
- On the other hand, young Saitama is ranked 10th in the character popularity poll.
- Near the beginning of the manga's story, the color of Saitama's cape was red (House of Evolution Arc) but was later changed to white (Giant Meteor Arc).
- Saitama's favorite food is hot pot.
- According to Genos, Saitama's true potential does not lie within his appearance, but rather the way he did his best on training himself to become a true hero causing him to receive his super strength after three years of training.
- Due to his unimpressive appearance, many enemies and allies tend to think that he is weak at first glance; only Carnage Kabuto, Boros, and Orochi could sense his real strength before engaging.
- As confirmed in the compus notebook from the limited edition DVD set for season 1, he prefers casual clothing such as flip flops because there the easiest to change out of and kick off if a battle were to happen.
- One-Punch Man author ONE came up with Saitama's rather simplistic design when thinking about how many "cool looking heroes there were."
- Saitama's name is most likely derived from the Saitama Prefecture located in Japan, where ONE currently lives and first started drawing the series.
- Before becoming a hero, Saitama worked part-time at a convenience store. He also used to work at festivals part-time when he was younger.
- As shown in some occasions, Saitama is quite stingy with money, in which he often tries to obtain foods in unconventional means, like hunting in the forest or even scavenging some parts of Mysterious Beings as food.
- Saitama still performs his workout routine.
- Murata states that if Saitama had not hit the moon, he would have only needed to blow to propel himself. However, this is just his speculation and has not been stated by ONE.
- Saitama still grows hair everywhere else on his body besides his head.
- Saitama has a cameo appearance as a Senior Explorer (Alchemist) in Alchemia Story, a mobile game by Asobimo. He guides the player on how to create Synthesis Items later on while he brags about his feats. He even has a similar physical appearance in the game but with a huge difference in his eyes and clothes.
- He got his suit from an old retired tailor who would repair his track-suit for him, he was embarrassed to wear it at first, but now cherishes it.
- Murata speculates that the limiter is not the secret to Saitama's strength.
- According to the databook:
- What he likes is seaweed, Chinese cabbage, and new products of dubious value.
- The hidden meaning behind Saitama's cactus is it remains unchanged no matter how it is taken care of.
- Saitama's known class promotions: C-Class Rank 388 (Start) → C-Class Rank 342 (After solving the Sonic event) → C-Class Rank 5 (After solving the Meteor event) → C-Class Rank 2 (Before the Seafolk invasion event) → C-Class Rank 1 (after the Deep Sea King incident) → B-Class Rank 101 (Promoted to B-Class) → B-Class Rank 63 (At S-Class meeting) → B-Class Rank 33 (Between King and Garou introduction and after solving the Dark Matter Thieves invasion) → B-Class Rank 7 (Before meeting Fubuki) →
- And finally after the Monster Association Arc: A-Class Rank 39 (Promoted to A-Class)