Main Characters | Hero Association (S-Class Heroes) | Neo Heroes | Villains and Monsters (Monster Association) | Others
- Foil: To the Hero Association's Pro Heroes:
- Pro Heroes fight crime with their own tools and abilities, while the Neo Heroes enhance their strength with Powered Armor.
- Pro Heroes fight individually or in small groups, while Neo Heroes are organized like a military.
- Hypocrite: Despite their claim that the Hero Association is only built on appearances, Neo Heroes livestreams all their battles.
- Powered Armor: All of their heroes wear one which enhances their ability. Wherever they got the suits from sure as hell wasn't legal, as Genos notes.
- Red Shirts: Several lower class and even some Neo Leaders became this in their first day of work.
- Soldier vs. Warrior: The Soldier to the Hero Association's Warrior. The Hero Association has far stronger members on an individual level but they operate without a unified leadership, and there are several factions within vying for power. The Neo Heroes tend to be weaker on average, but they make up for it with their battle suits, greater numbers, and better organization directing their efforts.
- Unskilled, but Strong: Their battle suits give them strength on par if not even greater than an A-Class hero, but most of them lack the skill to use them which is how several of them got fatally injured when the threat they faced was able to take their hits and/or penetrate their armor.
- Unwitting Pawn: Child Emperor suspects the suits the Neo Heroes use might have come from Metal Knight, which would give him complete control over them whenever he wants. The story implies the suits actually come from the Organization which also boasts advanced technology and has let others use them under suspicious circumstances to gather battle data for further improvement.
The Neo Heroes has yet to present its ranking system, they have 2000 hero candidates in mind, compared to the Hero Associations total 600 highest active number; among those they boast about already employing heroes perfectly comparable to the HAs S-Class ranks who are placed as Neo Leaders.
- The Ace: According to himself and Mccoy, he is the strongest member of the Neo Heroes.
- Despite his claims of true justice his attempt to kill Amai Mask who revealed his identity as a monster to save people can be seen as precautious at best or unjustifiable and glory seeking at worst since Amai Mask has not harmed any civilians.
- He created Neo Heroes, because he considers the entirety of the Hero Association to be corrupt and yet various staff members of the Neo Heroes were a part of the Hero Association with some of them even part of said corruption and Neo Heroes is actively offering heroes to switch over. On top of that two of the Neo Leaders were criminals before joining and are now under the Neo Heroes' protection and are allowed to carry weapons which includes Ryumon's entire gang of 400.
- Informed Ability: His claim of being the Neo Heroes' strongest hero is already questionable due to most of his power coming from his battle suit and his visible struggle against the Dragon-Level threat he faces during which he notes that even one mistake could lead to his death. In fact, he hasn't even fought a monster once before he's introduced into the story.
- The Leader: Is the founder and leader of the Neo Heroes.
- Sketchy Successor: Claiming to be Blast's son is already questionable in its own right, with the only evidence supporting it being his own word and the mystery surrounding his father making it both plausible and implausible at the same time. Not helping the matter is that his powers seem to come from technology and his visible struggle against a Dragon-Level threat in which one hit could spell his death.
- Skilled, but Naïve: He is strong enough to defeat Demon-Level threats, but is rather implied to have a Horrible Judge of Character since two Neo-Leaders used to be criminals and his executive McCoy is a part of the Hero Association's corruption and. He also never fought monsters before founding Neo heroes and underestimated ther strength.
- Teen Genius: He was able to found and create Neo Heroes while being 16 and is also considered the organizations strongest hero.
- Boringbut Practical: We get a look at how his group takes down monsters when they face a giant snail - they attack it with poisoned weaponry and drive it into a head-on collision with group members holding long spears. Not exactly as flashy or effortless as the S-Class would make it look, but it works.
- Informed Ability: The Hero Association considers him to S-Class in strength, yet his claim to fame is defeating one Demon-level threat he and his Hunters struggled against, with five Hunters dying in the process. Not exactly a good look since S-class by definition are capable of soloing Demon-level threats.
- Only Sane Man: He is the only one who questions if it is a good idea to supply Ryumon and his gang with weapons since they used to be criminals before supposedly reforming and joining Neo Heroes.
- Vigilante Man: Before he was hired.
- Fights Like a Normal: The only Neo Hero to fight without using a suit, since he feels they can't match the latent potential of flesh.
- Informed Ability: He's supposedly as strong as Darkshine, but he doesn't get a chance to properly measure the difference in their strength since Darkshine is in a massive funk when they meet.
- Nice Guy: Is respectful enough of Darkshine's mental breakdown to avoid pressing the issue for a confrontation when he realizes.
- He also saves a Hero Association member from being killed by a group of monsters, being thankful that he was able to reach him in time.
Voiced by: Masaya Matsukaze (Japanese), Alan Lee (English)
- The Ace: He is considered a legend for winning 4 Super Fight tournaments in a row.
- Adaptational Personality Change: His webcomic self never went through the Character Development his manga version did, so he's still cocky and lazy as ever, and joined the Neo Heroes only because they promised him a fat paycheck.
- Ain't Too Proud to Beg: Beaten up by Gouketsu and surrounded by crow monsters in his weakened state, Suiryu doesn't hesitate to put aside his pride and ask Bakuzan, who's been watching all the while and still more or less at full strength, for help. Bakuzan proceeds to eat all the remaining monster cells instead.
- When he's beaten down to the point of only being able to crawl, he tries begging Bakuzan to spare him (though he drew the line at licking his feet) and shortly after cries out for a hero to save him — anyone at all. Thankfully, this time, Saitama comes to rescue him, Sneck, and Max from certain death.
- All Chinese People Know Kung-Fu: He wears a traditional uniform used in Chinese martial arts, with a black and white top sporting long sleeves and has star shaped decor in front. ONE has stated that in the real world he'd be Italian, though.
- Anti-Villain: Despite his Social Darwinist beliefs and a little arrogance, he is not a bad guy and just serves as a Hero Antagonist to Saitama until Gouketsu's arrival.
- Arrogant Kung-Fu Guy: In the traditional sense. But even more so regarding his lifestyle choice.
- Beauty Is Never Tarnished: Somewhat. Bakuzan punches his teeth in and rips off his hair, but otherwise he's not too disfigured.
- Blood Knight: Subverted. He claims he wishes to feel the thrill of a real fight, just like Saitama and Boros, but the moment he's faced with a situation where he might actually lose, he immediately loses all composure and flies into a rage. He outright states he doesn't find losing to be fun, which contrasts Boros, who had the time of his life even though he completely lost.
- Break the Haughty: Starts when he is completely defeated by Gouketsu. His pride is shown to further break down from his former arrogant nature after desperately asking for help from Bakuzan, knowing full well he cannot win with his strength alone. Bakuzan refuses and he is saved by the same heroes he mocked before. And, in the end, he is once again brutally attacked by monster-Bakuzan, leaving him heavily injured and unable to do more than scream for some hero, any hero no matter how weak, to come save him. Luckily, it's Saitama who comes to his rescue.
- Brilliant, but Lazy: By his own admission, he's never trained particularly hard and would sometimes neglect his master's lessons to spend the day picking up girls instead. At the present day, he admitted that he hasn't even bothered practicing his martial arts at all in the past few years and primarily entered the current Super Fight tournament because he was low on cash. Even so, he's easily leaps and bounds ahead of the A-Class heroes and one of the strongest martial artists seen yet solely through his natural talent.
- Canon Immigrant: Was not in the original webcomic version of the Monster Association arc, like most of the other tournament contestants. He was eventually imported back into the webcomic, albeit without his Character Development.
- The Casanova: He enjoys hitting on pretty girls in his spare time. He also only decided to fight the transformed monsters if one of the presentation girls at the tournament would go out with him.
- Charles Atlas Superpower: Good lord! He's strong enough to split the tournament ring in two and lift half of it by stomping his foot all from his martial arts.
- Clothing Damage: Saitama's punch (which he stopped just in time) rips off Suiryu's shirt and shows off his Heroic Build.
- Comes Great Responsibility: Inverted. He believes, since he's insanely strong, that he has the right to just relax, have fun, and do anything he wants. Even when the other competitors turned into monsters, he only faced them in exchange for a date with a girl. Likewise, he believes that heroes who fight for such things as a sense of duty or justice to be either corrupt hypocrites or ineffectual weaklings. He rethinks this position after he's left broken in body and spirit by Gouketsu and later, Bakuzan, and he finally understands what it's like to be utterly powerless against an implacable foe with no one to come to your rescue. Combined with seeing Sneck and Lightning Max fearlessly stand up to Gouketsu despite being hopelessly outmatched to give him a chance to escape and later being saved by Saitama after he's left in utter despair at his situation prompts him to resolve to become a hero himself.
- Curb-Stomp Battle: He defeated Lightning Max, and subsequently Sneck, with a single attack. Receives one from Saitama and, later, Gouketsu.
- Disqualification-Induced Victory: The only way he could have won against Saitama, with the latter being disqualified when his disguise was revealed. He didn't like it to say the least.
- Foil: To Saitama: both are very strong and wish to have a real challenge, but while Saitama is bored of his situation, Suiryu is happy and relaxed, claiming he can do whatever he wants (due to his beliefs). It's actually invoked by Suiryu himself, noticing Saitama specializes in punches, so he decides to use kicks.
- Is also one to Genos, both being extremely powerful individuals who were changed by Saitama. Both Suiryu and Genos didn't think much of heroics until they faced an insurmountable obstacle and were saved by Saitama, who showed them both what a true hero is like. Suiryu even asked if he could be Saitama's disciple too but Saitama had already learned his lesson with Genos and refused.
- Empowered Badass Normal: Assuming the webcomic version of him shares the same S-class skills and capabilities of the manga version, after joining the Neo Heroes, he wears the Powered Armor they provide which is already potent enough to make C-Class heroes stronger than A-Class heroes.
- The Gift: Despite his youth and his decidedly laid back attitude towards his own martial arts (seeing it only as something to impress girls and win tournament money with), his natural raw skill and power would easily qualify him as an S-Rank hero. Bakuzan outright admits that, with how strong Suiryu is at present while still having the potential to grow stronger, he'll never be able to match up to him as a human, hence, why he decided to become a monster.
- Hypocrite: He's very fond of mocking and taking others lightly because he's stronger than them, but the moment Saitama does the same to him, he gets pissed off. He also looks down on heroes as being condescending and self-serving while performing deeds in return for favours even though he's guilty of the same thing.
- Jerk with a Heart of Gold: While he's certainly arrogant, condescending, and self-centred, Suiryu's not really a malicious person at heart. He's also genuinely grateful to Lightning Max and Sneck for saving him in his hour of need, admitting to himself that he was wrong about heroes, and later tries to hold back Saitama from going after Gouketsu after saving him from Bakuzan despite being beaten so badly he can't even stand.
- Jerkass Has a Point: His criticisms of heroes may not apply to guys like Mumen Rider or Saitama (on a good day), and he's just as guilty of using his power to do whatever he wants, but he's not wrong that the Hero Association is corrupt and doesn't actually care about protecting people.
- Let's Get Dangerous!: After seeing how strong Saitama really is, he stops using only kicks and fights with all his strength.
- Long-Haired Pretty Boy: He is this, and went out with a lot of girls. Bakuzan "fixes" this by punching most of his teeth out and ripping off his hair.
- Mr. Fanservice: He has many a Shirtless Scene.
- Normal Fish in a Tiny Pond: The source of his pride. He's legitimately strong and would fit into the lower ranks of S-Class perfectly, but he's limited his world view to what he sees in the tournament ring. Fighting only people much weaker than him has blinded him to just how many monsters and heroes out there are stronger than him. He finally understands this once he fights the Dragon-level Gouketsu and realizes that for all his strength, he can't make the monster even blink.
- Oh, Crap!: He's practically drenched in fear-sweat after his shirt is shredded right off his body just from the wind of Saitama's punch. It's very clear that he's never faced an opponent who was actually a threat to him, much less an opponent who outclassed him completely. It happens again when he realizes that he can barely make Gouketsu flinch and he's not taking it seriously.
- Pride Before a Fall: He enters the tournament smug and assured of his invincibility. He then gets his ass kicked several times over, and has his world view, especially his disdain of heroes, utterly broken.
- Rapid-Fire Fisticuffs: Kick version. Then he uses a mix of the two, that obviously has no effect on Saitama.
- "The Reason You Suck" Speech: Gave this to Sneck, realizing that most heroes do their job not for justice but only for self-satisfaction, pride, and ego.
- Slipknot Ponytail: When receiving the punch from Saitama, his ponytail comes off.
- Smug Super: Is very confident in his abilities, is likely as strong as an S-Class hero, and loves taking time out of his day to remind you of this. Learning firsthand he's not at the top of the pecking order via repeated humiliation humbles him a bit.
- The Social Darwinist: He believes strongly in the philosophy of natural selection, where the strong will always prevail no matter what.
- Sore Loser: Despite claiming that he wanted a fun battle against an opponent that he could cut loose against, the moment it becomes clear that Saitama is much stronger than he is, he immediately throws what is essentially a temper tantrum, drops his carefree attitude and tries to administer a brutal No-Holds-Barred Beatdown on him. When Saitama calls him out on this he actually retorts that he doesn't find losing fun.
- Trauma Conga Line: Suiryu entered the tourney expecting to win the prize money, have a good fight or two, and maybe score a date along the way. What he got instead was the worst day of his life. To whit,
- It begins when he fights Saitama. Despite his best efforts, he can't do anything to Saitama, and wins only via technicality, but he brushes it off.
- Gouketsu then enters the picture, and transforms several other fighters into monsters. Suiryu fights them in exchange for a date with a pretty girl, and beats them with moderate difficulty, but gets rewarded by being beaten halfway to death by Gouketsu and his three crow monster henchmen. Suiryu realizes he's outmatched and throws away his pride to ask Bakuzan for help, only to have Bakuzan refuse and transform into a monster instead. He's saved from one killing blow at the last second by Sneck and Lightning Max, who he disparaged for being heroes and weaker than him, only to watch in horror as they sacrifice themselves to buy him time to escape. He tries...
- ... but gets blocked and beaten down even further by the now fully transformed Bakuzan. All he can do at this point is crawl along the ground with tears in his eyes and scream out for a hero, the ones he looked down on so much, to come save him. It's this final moment of humility that causes Saitama, his last tournament opponent, to come to his rescue.
- Unskilled, but Strong: Played with, and nowhere near to the level as Saitama, since, while he does have training, he's a Brilliant, but Lazy prodigy who, despite neglecting his training, is powerful enough to qualify as an S-Class Hero.
- Villainous BSoD: While it's a bit of a stretch to call him a villain, he didn't take his "loss" against Saitama very well. However, he snapped out of it pretty quickly and decided to just forget about the encounter.
- Willfully Weak: He decides to use only kicks to contrast himself from Saitama but can also fight with punches as well.
- The Worf Effect: He is heavily outmatched by Gouketsu, who is completely unfazed by Suiryu's most powerful attacks.
- Worthy Opponent: Subverted. While he does search for strong opponents and takes some pleasure fighting someone who can actually make him work for a victory, if it actually seems like he's going to lose his playful attitude will immediately do a 180.
- Axe-Crazy: He is clearly not the most stable person, since the first he says once hearing Neo Heroes is allowed to fight crime is that they can carry guns now.
- Hazy Feel Turn: He was originally a criminal, but joined Neo Heroes to become a hero although his sanity and sincerity in it is rather questionable.
- Jerkass: He rejects an offer of teamwork from a Hero Association member, calling him a small fry and "thanking" him for losing to the monsters and strengthening him and his gangsters' image.
- Crimefighting with Cash: He is one of Neo Heroes' investors and paid 200 billion yen for his own suit. This is deconstructed however since he lacks the fighting skills or training necessary to fight a Demon-Level threat which caused him to lose very badly.
- Epic Fail: He is unable to deal any amount of damage to the monster he was fighting and it is highly implied, he was defeated instantly!
- Fiction 500: He has set aside the highest budget for his personal equipment and is also one of Neo Heroes' investors.
- Powered Armor: He spent 200 billion yen on it and claims that it is more advanced than the standard suit Neo Heroes used. It still failed to defeat the Demon-Level threat he was fighting.
- Body Horror: She modified through cyborg parts in which she at least replaced all her limbs, took drugs to strengthen herself further and went trough brain surgery to gain psychic powers which all left only 29% percent of of her body unmodified.
- Foil: Towards Amai Mask:
- Amai Mask started out as a hero due to his believe in inner beauty and morality despite his original ugly appearance and became an idol to support the Hero Association, Webigaza is an idol who became a hero and joined Neo Heroes to improve her own image and catch up to him in popularity.
- Amai Mask's body transformed into a mysterious being due to his complex about his appearance, while Webigaza willingly modified 71% of her own body to rival Amai Mask.
- Webigaza fights monsters with flashy moves and powers, while Amai Mask fights monsters using his sheer strength to kill them swift and instantly.
- Green-Eyed Monster: Towards Amai Mask due to him outshining her in popularity.
- Power at a Price: It's implied her modifications have reduced her lifespan by a lot.
- Psychic Powers: She gained them through brain surgery.
- Stepford Smiler: Her squad notes how fake her smiles for her livestream are, and she's likely insane beneath it all.
- Unknown Rival: The reason she became a hero was to surpass Amai Mask, but it is implied he has not even met her at all.
- Victory Is Boring: She has defeated Amai Mask as an idol due to him being forced to retire after revealing his identity as a monster, but she is very dissatisfied since she wanted to defeat him with her own ability.
- Curb-Stomp Battle: Similar to Zaedats, he gets easily wrecked by a Demon-level threat. His fate is unknown as his prone body was last seen being carried off by Destro and Erimin.
- Foil: Can be seen as this towards Gearsper. Gearsper is a C-Class hero with psychic powers who was chosen to help in the Monster Association raid and despite his Power Incontinence was able to support his team and utilize his inate powers which potentially rivaled Tatsumaki against Nyan, a Dragon-Level monster, which also showed why he was chosen on the team. Infelsinave is a Neo-Leader with divine powers who supposedly should be on par with S-Class, but was easily wrecked by a Demon-Level, which makes the choice of him becoming a Neo Leader rather questionable aside from his influence.
- Informed Ability: He supposedly has divine powers and is on par with the Hero Association's S-Class, but he was severely injured on his first day with his fellow Neo Heroes even saying that he should not fight against threats of Demon and above.
- Take That!: He is possibly one towards the Isekai genre since the church he founded is called the "Church of Otherworldy Reincarnation" which has amassed many followers in recent years just like how the genre gained popularity in real life, but it is implied to be a cult instead of a true religion.
Neo Hero Candidates
- Jerkass Has a Point: He is a rather abrasive person, but he is correct in that some of the choices of Neo Leaders are rather questionable especially since both Zaedats and Infelsinave were fatally injured on their first day.
- Cyborg: He modified his own body to particpate in a cyborg fighting tournament.
- Oh, Crap!: He has this reaction when seeing how high the body modification percentage was on Webigaza and two Neo Heroes staff members.
- Stat-O-Vision: His mechanical eye can read how much a person has modified their own body.
Destro and Erimin
- Ambiguous Robots: Despite looking perfectly human, Destro and Erimin have had their bodies modified by 94 and 95% respectively, when most humans only ever go 30% and 60% is considered to be extremely risky. This suggests they really aren't cyborgs, but rather robots posing as humans.
- Cyborg: Koko identifies them as such, but it's very possible they aren't.
- Punny Name: Destroy and Eliminate.