# Discover every hero in One-Punch Man who knows Saitama‘s strength. We rank them not by power, but by their unique reactions—from worship and fear to friendship and rivalry.
MASSIVE SPOILER WARNING: This article contains major spoilers for the One-Punch Man manga, including the Monster Association and Cosmic Fear Garou arcs. Proceed at your own risk.
Ngetrenz – What happens when you meet a god? Not a deity of myth and legend, but a bored, balding god in a cheap tracksuit who worries more about supermarket sales than the fate of the universe. This is the central, brilliant paradox of Saitama, the One-Punch Man. His power is absolute, a cosmic joke played on a world filled with heroes and monsters desperately striving for the next level. But what happens to the few who peek behind the curtain?
This isn’t a power-scaling list. The question of who could beat whom is irrelevant when one of the subjects is infinity itself. Instead, we’re exploring a far more interesting question about who knows Saitama’s strength and how that earth-shattering knowledge reshapes their reality. This list ranks the handful of heroes who have truly comprehended the limitless nature of Saitama’s power, not by their own strength, but by the transformative impact of this revelation on their lives, their purpose, and their very souls.
The reactions of these few chosen witnesses are more than just individual character moments; they are the narrative’s primary tool for illustrating the profound loneliness that comes with Saitama’s absolute power. Each reaction—from worship to friendship to scientific curiosity—defines a different facet of the unbridgeable gap between him and the rest of humanity. By analyzing how others react to his strength, we are indirectly analyzing the very source of his existential crisis.
The Definitive Ranking of Reactions to Saitama’s True Power
#1: Genos
Genos’s enlightenment was as violent and absolute as Saitama’s power itself. It happened during their first “sparring match” in a remote canyon, a moment immortalized in Chapter 17 of the manga. After witnessing Saitama casually dispatch monsters, Genos, the Demon Cyborg, demanded to be taken on as a disciple. To prove his worthiness, he unleashed his full, city-block-leveling arsenal. For a breathtaking sequence, he demonstrated the pinnacle of Dr. Kuseno’s technology, a whirlwind of incinerating blasts and machine-gun blows. And it meant nothing.
Saitama, with a bored expression, simply appeared behind him. The true moment of revelation wasn’t a punch that landed, but one that was deliberately pulled. Saitama’s fist stopped a hair’s breadth from Genos’s face, yet the sheer force of the displaced air was enough to obliterate the massive rock formation behind him for hundreds of meters.
In that instant, the full, horrifying scale of Saitama’s true power revealed itself. It wasn’t just strong; it was a different state of being, a power that could erase him from existence without even making contact. This understanding was later deepened during their second, more emotionally charged rematch, where Genos realized the gap had only widened, and Saitama’s casual lack of fear was the ultimate proof of his own irrelevance in a fight.
The Genos’s reaction to Saitama is ranked number one because it is the most profound and life-altering of any character in the series. His entire existence was overwritten. His original quest for the “Mad Cyborg” wasn’t abandoned, but it was subsumed by a new, all-consuming mission: to observe, document, and comprehend the living miracle that is Saitama. He went from a vengeful weapon to a zealous scribe, his notebooks filled with the “teachings” of a man whose greatest wisdom is often related to hot pot ingredients.
This initial devotion was almost religious. Genos saw in Saitama the absolute strength he believed was necessary for justice, the finish line to his own desperate race for power. However, what makes his reaction so transformative is its evolution. Through living with Saitama, he began to learn more than just the “secret” to strength. He learned about mundane human concerns—grocery sales, rent, the simple pleasure of sharing a meal.
These seemingly trivial lessons in humanity began to temper his mechanical single-mindedness, slowly transforming him from a walking weapon into a more complete person who could show compassion and humility. The Genos’s reaction to Saitama is a journey from deification to humanization, making it the most dynamic of all the One-Punch Man character reactions.
As a cyborg, Genos’s core function is data collection and analysis. His entire worldview is built on quantifiable metrics: energy output, speed, durability. The sparring match presented him with a data point that was an impossible outlier—a being with seemingly infinite power that broke every known parameter. His response was to default to his core programming: observe and analyze. His endless note-taking and detailed reports are not just a running gag; they are his fundamental method of processing a phenomenon that his logic processors cannot handle.
He is, in essence, attempting to write the scripture of a new god in binary. This “scientific deification” is a form of worship uniquely his own. It’s not blind faith; it’s an unending scientific inquiry into a living deity, making the Genos’s reaction to Saitama the most complex and character-consistent in the series. This is a crucial point for understanding the dynamic between the few heroes who know about Saitama.
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#2: King
Unlike Genos’s explosive revelation, King’s awareness was a slow-burning, creeping dread. For years, he had been hailed as “The Strongest Man on Earth,” a reputation built entirely on being in the right place at the right time—namely, standing near the wreckage of a monster Saitama had just obliterated. The full confirmation came during the harrowing battle against Elder Centipede. With Genos, Bang, and Bomb all pushed to their limits, the colossal monster turned its attention to King.
Cornered, with the world watching, King did the only thing he could: he bluffed. His heart hammered in his chest, creating the terrifying “King Engine” sound that so many monsters had come to fear. But this time, it was pure, unadulterated terror. He knew he was seconds from death. And then, Saitama arrived, asking him to move so he wouldn’t get hurt. With a single “Serious Punch,” Saitama didn’t just defeat Elder Centipede; he vaporized its city-length carapace, turning it into dust. In that moment, the horrifying truth King had long suspected was solidified: the unassuming, video-game-loving bald man was the true source of his god-like reputation.
King’s reaction is the most human and relatable of anyone who knows Saitama’s strength. It is a potent cocktail of three distinct emotions: crippling fear, immense relief, and the foundation for a genuine friendship. The fear is constant; he lives in perpetual anxiety that his fraud will be exposed or that a monster will finally call his bluff when Saitama isn’t around. The relief is euphoric; every time Saitama saves him, he is granted a new lease on life.
But the most important element is the friendship. Unlike every other character, King does not worship Saitama’s power; he’s terrified of the situations it attracts. He doesn’t want to learn from Saitama or analyze him. He just wants to hang out, eat snacks, and play video games with the one guy who knows he’s a total fraud and doesn’t care. This shared understanding is the core of the King and Saitama’s secret. It allows for a level of normalcy and casual intimacy that Saitama cannot find anywhere else. For King, knowing the secret is a burden; for Saitama, having someone know it is a blessing.
Their friendship is not one-sided; King provides a crucial psychological anchor for Saitama. Saitama’s central tragedy is that his omnipotence has rendered his life devoid of challenge, leading to boredom and emotional apathy. King, while physically the weakest, is consistently portrayed as Saitama’s equal or superior in the realm of video games, often beating him soundly. When Saitama loses a match, he experiences genuine frustration, a competitive drive, and a desire to improve—the very emotions he can no longer feel in a real fight.
The King and Saitama’s secret is therefore not just about protecting King’s reputation, but about preserving the one sanctuary where Saitama can feel human again. King, the “fake” hero, is the only person who provides Saitama with a real, humbling challenge, making their bond the most important in the series for Saitama’s own psychological well-being.
#3: Zombieman
Zombieman‘s path to understanding was not through direct observation but through intellectual pursuit. His journey began with a conversation with a reformed Dr. Genus, the brilliant and disgraced scientist from the House of Evolution, in Chapter 89 of the manga. Genus, humbled by his own defeat at Saitama’s hands, had abandoned his quest for artificial evolution and instead turned his intellect to a new question: how was Saitama possible?
He presented Zombieman with a groundbreaking theory: every living being possesses a “limiter,” a conceptual barrier placed by “God” to restrict growth and maintain sanity. To grow too powerful is to risk becoming a mindless monster. Genus theorized that Saitama, an ordinary man with no special potential, had somehow, through sheer force of will and effort, broken his limiter, granting him access to limitless power. This conversation planted a seed in Zombieman’s mind. Driven by this new, paradigm-shifting knowledge, he began to see Saitama not as just another hero, but as the living, breathing proof of a world-changing biological law.
Zombieman’s reaction is unique in its complete lack of emotion. There is no awe, no fear, no worship. It is the cold, focused reaction of a scientist who has just discovered a new law of physics. For him, the question of who knows Saitama’s strength is secondary to the question of how that strength was obtained. He sees Saitama as a puzzle to be solved, a biological miracle to be reverse-engineered.
This pursuit is deeply personal. Zombieman’s own power, boundless regeneration, makes him immortal but not invincible. He is often forced to endure gruesome, protracted battles, winning through sheer attrition. He desires overwhelming power not for glory, but to end threats more efficiently and protect more people. Saitama, therefore, represents the answer to his ultimate quest: to find a way to remove his own limiter and achieve the strength necessary to fulfill his heroic ideals. His is one of the most goal-oriented of the One-Punch Man character reactions.
Zombieman’s quest personifies the core philosophical question of One-Punch Man: What defines the limits of potential? The series repeatedly explores different paths to power—monsterification, technology, martial arts. Dr. Genus provides the unifying theory of the “limiter,” and Saitama is the impossible result of shattering it. While Garou’s journey shows the process of raising one’s limiter through monsterification, Zombieman is the only character who, upon learning the theory, decides to pursue breaking his own through methodical, scientific means. His reaction thus transforms the “limiter break” from a convenient plot device into a tangible, in-universe scientific and philosophical quest, making it one of the most thematically significant reactions among the heroes who know about Saitama.
#4: Silver Fang (Bang)
Bang, the S-Class Rank 3 hero and a martial arts grandmaster, had his moment of clarity during the Z-City meteor crisis. Faced with a Dragon-level threat that was about to annihilate the city, Bang, a pinnacle of martial arts technique, and Genos, a pinnacle of technology, were utterly helpless. Metal Knight’s advanced weaponry failed, and Genos’s most powerful blasts did nothing. They could only watch as the city-killer descended.
Then Saitama arrived. Leaping from a rooftop, he met the meteor head-on with a single, artless punch. The result was not a skillful deflection or a strategic redirection; it was pure, overwhelming force that shattered the celestial body into a shower of fragments. In the aftermath, Bang’s quiet, internal acknowledgment that this B-Class hero was “many times stronger” than himself was the key moment. He didn’t just witness immense power; he witnessed a power that operated outside the known rules of his world, rendering a lifetime of honed technique irrelevant.
Bang’s reaction is one of quiet, humbled respect. As a master who has dedicated his entire life to the perfection of technique through his “Fist of Flowing Water, Crushed Rock,” he recognized something that transcended skill entirely. This is the core of what is Silver Fang’s opinion of Saitama: he sees a power that is not to be challenged, envied, or even fully understood, but simply acknowledged as a force of nature. He doesn’t offer to train Saitama to make him better in a condescending way, like Flashy Flash does; he offers to show him some moves out of a master’s instinct to share his art, all while knowing that Saitama’s power needs no such refinement.
This reaction is a profound thematic commentary on the limits of discipline and skill in a world where gods can walk the earth. The entire philosophy of martial arts, particularly as depicted in fiction, often centers on the idea that refined technique can overcome raw, brute force. Bang is the living embodiment of this philosophy.
The meteor, however, was the ultimate “brute force” problem—an object of such immense mass and kinetic energy that it could not be parried or deflected. Saitama solved this problem not with technique, but with an infinitely greater application of brute force. This event forced Bang to confront the absolute ceiling of his worldview. His graceful acceptance of this fact, rather than bitter denial, is what defines him as a true master. His reaction is therefore a deeply philosophical one about the nature of strength itself, making it one of the most mature One-Punch Man character reactions.
#5: Flashy Flash
For Flashy Flash, S-Class Rank 13, the moment Saitama’s true power revealed itself was a claustrophobic nightmare deep beneath the earth. During the chaos of the Monster Association arc, he, Saitama, and the small monster Manako found themselves navigating the subterranean tunnels. Confident in his status as the fastest hero, Flashy Flash decided to “test” the B-Class upstart.
In the pitch-black confines, he unleashed his ultimate speed, a velocity that makes him imperceptible to almost any other being. This speed is the foundation of his S-Class status, his pride, and his entire identity. And the bald man in the jumpsuit effortlessly kept up. The manga panels brilliantly depict Flash’s mounting horror as Saitama not only dodges his every move but casually gets ahead of him, treating the entire life-or-death encounter like a leisurely stroll. When he finally launched his “Flashy Kick,” a move meant to end any fight, Saitama simply sidestepped it, his fist waiting, a silent promise of annihilation that Flashy Flash barely comprehended before it was over.
Flashy Flash’s reaction is the polar opposite of Bang’s humble acceptance: it is the violent shattering of a massive ego. Confronted with irrefutable proof that his defining trait—his speed—was utterly meaningless, his mind scrambled to protect itself from the implications. His reaction progressed through textbook psychological defense mechanisms:
- Disbelief: He simply cannot process what he is seeing, his internal monologue filled with confusion and shock.
- Denial: He refuses to accept the reality of the situation. He rationalizes that Saitama must have some hidden potential, framing the encounter as a “test” that Saitama passed.
- Recontextualization: In a desperate ploy to regain a sense of superiority, he declares that he will take Saitama on as his disciple. This is a classic psychological maneuver to reframe the power dynamic, allowing him to maintain his position at the top, at least in his own mind. This is how some of the heroes who know about Saitama cope with the crushing cognitive dissonance.
This desire to make Saitama a “rival” or “pupil” is not just simple arrogance; it is a necessary defense mechanism against existential obsolescence. For a prodigy like Flashy Flash, whose entire identity is built upon being superlative, accepting Saitama’s effortless superiority would be to accept that his own life’s work, his grueling training, and his very identity are fundamentally meaningless. By framing Saitama as a rival to be surpassed, he preserves his own relevance and gives himself a new, albeit impossible, goal. This protects his ego from complete collapse, making his reaction a fascinating and psychologically complex case study among those who know Saitama’s strength.
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#6: Blast
Blast, the long-absent S-Class Rank 1 hero, is the only character who operates on a similar cosmic scale to Saitama. His moment of understanding came during the climax of the battle against Cosmic Fear Garou. When Garou, empowered by “God,” began to flood the Earth with cosmic radiation, Blast intervened, not just to fight, but to manage the dimensional fallout. He witnessed firsthand a level of power that could damage the “dimensional seal,” requiring the combined effort of his interdimensional team to contain the energy leakage.
The ultimate proof came when Saitama and Garou clashed with their “Serious Punch².” The resulting shockwave was so immense that Blast and his team had to warp the energy away from Earth. The visual representation of this event—a vast sphere of blackness appearing in the cosmos, devoid of stars—was a testament to a power that could erase galaxies. For Blast, this was the moment Saitama’s true power revealed its universal implications.
Of all the heroes who know about Saitama, Blast is the only one who isn’t completely shocked or psychologically broken by the revelation. His reaction is not one of awe, fear, or rivalry, but of professional acknowledgment. He is a being who deals with interdimensional threats and the power of “God” as his daily business. While Saitama’s power is clearly at the absolute apex of anything he has ever encountered, it exists within a context he can understand.
He treats Saitama as a powerful, unpredictable variable in his ongoing cosmic war—a potential ally of immense value, but also a potential danger to the fabric of reality itself. He doesn’t see a disciple or a god to be worshipped; he sees another major player on the board, a “fist that turned against God”.
Blast’s primary role in the narrative is to finally provide a yardstick for Saitama’s power. Before his appearance, Saitama was simply “infinitely strong” in a vacuum. Blast’s presence and reaction serve to contextualize that strength. By showing that Saitama’s battles have consequences on a dimensional level, the story officially elevates him from an unbeatable planetary hero to a genuine cosmic entity. Blast’s reaction is less about his personal feelings and more about his narrative function: to confirm that the scale of the story has now expanded to the universal level, and that Saitama is at the very center of it. He is the one character who knows Saitama’s strength and can look at it without flinching.
Read More : Who is Blast? Everything We Know About OPM’s Number 1 Hero
Honorable Mentions: The Circle of Suspicion
A few heroes have witnessed enough to know Saitama is monstrously powerful, but they haven’t yet made the final leap to understanding his limitless nature. They exist in a state of profound suspicion, their worldviews cracked but not yet shattered.
- Amai Mask: After seeing Saitama casually defeat the Deep Sea King, a monster that had humbled multiple S-Class heroes, Amai Mask began to see him as the embodiment of an “ideal hero” in terms of absolute power. His understanding is growing, but he still lacks the full context.
- Tatsumaki: Her battle with Saitama left her physically and emotionally bruised. She is one of the few to have experienced his invulnerability firsthand and is infuriated by the fact that she, the most powerful esper, couldn’t even make him move. She acknowledges his superiority out of frustration but is too arrogant to process its true, infinite scale.
- Suiryu: The martial artist was saved from the brink of death when Saitama one-shotted the monster Gouketsu, a creature that had effortlessly defeated him and other powerful fighters. He knows Saitama is on a level beyond any monster he can conceive of, but he lacks the framework to comprehend infinity.
At a Glance: Hero Reactions to Saitama’s True Strength
| Rank & Hero Name | The “Moment of Realization” (Key Event/Chapter) | Core Reaction (One-Word Summary) | Psychological & Transformative Impact |
| #1 Genos | Sparring Match (Ch. 17) | Worship | Entire life purpose is reoriented around observing and understanding Saitama; evolves from a weapon of vengeance to a more humanized individual. |
| #2 King | Elder Centipede Fight (Ch. 94) | Friendship | A mix of terror and relief that fosters the only normal, human relationship for Saitama, providing him a much-needed anchor to reality. |
| #3 Zombieman | Limiter Theory (Ch. 89) | Curiosity | A purely scientific and philosophical reaction; sees Saitama as the key to his own quest to break his limits and achieve ultimate strength. |
| #4 Silver Fang | Meteor Destruction (Ch. 24) | Respect | The humbled acknowledgment of a master martial artist who witnesses a power that transcends all skill and technique. |
| #5 Flashy Flash | Underground Encounter (Ch. 137) | Rivalry | A shattered ego that copes through denial and a desperate re-framing of Saitama as a rival to preserve his own sense of self-worth. |
| #6 Blast | Cosmic Garou Fight (Ch. 167) | Acknowledgment | The professional recognition of a cosmic-level peer who sees Saitama as a powerful, reality-altering force to be managed. |
The Many Faces of Omnipotence
The spectrum of reactions to Saitama’s power is a mirror held up to the heroes themselves. Genos’s reaction to Saitama is one of religious worship that slowly blossoms into familial love. The King and Saitama’s secret forges a bond of true friendship out of shared fraudulence. Zombieman’s curiosity turns Saitama into a scientific equation. Bang’s wisdom allows him to offer quiet respect, Flashy Flash’s ego forces him into a one-sided rivalry, and Blast’s experience lets him see a peer.
These varied and complex One-Punch Man character reactions do more than just build the world; they define the central tragedy of its protagonist. Each reaction, in its own way, reinforces the barrier between Saitama and the world he protects. They see a god, a secret weapon, a biological anomaly, or a rival—but only King truly sees the man who just wants to play video games. The ultimate question of who knows Saitama’s strength is therefore a double-edged sword. For the few who find out, their world is changed forever. But for Saitama, their knowledge is just another reminder of the lonely, unbreakable silence at the top.
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Summary of Every Hero Who Knows Saitama’s Strength, Ranked By Their Reaction
- Core Thesis: The article ranks heroes who know Saitama’s limitless strength not by their power, but by the transformative psychological and philosophical impact of that knowledge.
- #1 Genos (The Worshipper): His reaction is the most profound, completely reorienting his life’s purpose towards understanding Saitama. His devotion evolves from religious awe into a deep, humanizing friendship.
- #2 King (The Friend): His reaction is the most human—a mix of terror and relief that forms the basis of the series’ most genuine friendship, providing a crucial anchor of normalcy for Saitama.
- #3 Zombieman (The Seeker): His reaction is purely scientific and goal-oriented. He views Saitama as a biological miracle and the key to his own quest to break his “limiter” for the sake of heroism.
- #4 Silver Fang (The Master): His reaction is one of humbled respect. As a master of technique, he recognizes a power that transcends skill and accepts it with wisdom rather than envy.
- #5 Flashy Flash (The Rival): His reaction is that of a shattered ego. Unable to accept being surpassed, he copes through denial and by reframing Saitama as a rival, a psychological defense to protect his identity.
- #6 Blast (The Peer): His reaction is one of professional acknowledgment. As a cosmic-level hero, he is the only one not shocked by Saitama’s power, viewing him as a powerful but understandable force on a universal scale.
- Central Theme: These diverse reactions highlight the isolating nature of Saitama’s absolute power, showing how different personalities cope with witnessing omnipotence.