All 13 One-Punch Man Characters Who Know Saitama's Secret (& When They Found Out)

Published Aug 31, 2026, 4:30 PM EDT Memory Ngulube joined Screen Rant in April 2024 as part of the Movies and TV team. Since then, she has written for the Perennials and Streaming team, covering a wide range of topics from new releases to old movies and TV shows. Memory is currently a Classic TV writer. Before joining Screen Rant, Memory was a freelance copywriter who specialized in email marketing and social media management. While she enjoyed her job, her true passion was always movies and TV. When she isn’t writing for Screen Rant, Memory can be found reading, baking (which is one of her passions), or watching her favorite K-drama. The source of Saitama’s power in One-Punch Man isn’t exactly a closely guarded secret, but many characters have overlooked just what the hero is capable of. To most of the Hero Association, he is simply an unremarkable-looking hero with a bald head, a cheap costume, and a seemingly mediocre ranking. Yet behind his nonchalant attitude is a man with power that has no bounds. The anime reveals why Saitama is very powerful early on. However, the explanation is so at odds with what Saitama can do that it reads like a joke, especially given the expectation that he got his powers through extraordinary means. According to Dr. Genus’ theory, Saitama removed his limiter, the natural restriction that prevents living beings from growing beyond their physical and psychological limits. As it is still just a theory, it is unclear whether Dr. Genus is right, particularly because even Saitama doesn’t really understand why he is so strong. This makes the characters who do know Saitama's secret very interesting. Some discover the truth after witnessing his strength firsthand, while others slowly piece together the evidence after seeing him accomplish things that should be impossible. Blast Blast is one of the strongest characters in One-Punch Man, so his recognition of Saitama's abilities carries considerably more weight than the assumptions of ordinary heroes. When Garou reaches his Cosmic Fear Mode, Blast arrives to confront him and quickly realizes that Garou has gained an extraordinary level of power through his connection to God. Blast is initially focused on containing the threat rather than Saitama, but Saitama becomes involved in the confrontation. As the battle escalates, Blast sees that Saitama and Garou's attacks have become powerful enough to threaten Earth, forcing him to intervene and redirect their energy into space. Black Sperm Introduced in the divisive One-Punch Man season 3, Black Sperm becomes fully aware of just how powerful Saitama is after witnessing the bald hero defeat Garou in his Cosmic Fear Mode. Having already experienced Garou's terrifying power firsthand, Black Sperm knows that the transformed Hero Hunter is on an entirely different level from most heroes and monsters. One-Punch Man Key Details Release Year 2015 Number of Seasons 3 Number of Episodes 36 Audience RT Score 61% Yet Saitama is able to overcome him with a single punch, leaving Black Sperm with undeniable proof that Saitama's strength is far beyond what he initially thought. Like Suiryu, Black Sperm also wants to make Saitama his master. After all, he would be much safer under the care of the bald hero. Garou Garou’s encounters with Saitama are one of the funniest moments in the anime. For a while, the One-Punch Man villain has no idea that the person who is responsible for thwarting his hero-killing plan is the bald man who seems to have no care in the world. After becoming Cosmic Fear Garou, he gains tremendous power and believes he has finally reached a level where he can challenge anyone. However, when he has to fight Saitama in his new form, he realizes that the bald hero is completely beyond him. The battle between hero and hero-hunter becomes the key to Garou's discovery. Saitama continuously grows stronger as the fight progresses, to the point that Garou's ability to copy his opponent's techniques and power cannot keep up. Garou eventually recognizes that Saitama's strength isn't simply the result of superior martial arts or a powerful technique but that his potential appears to have no meaningful ceiling. Bofoi Dr. Bofoi, better known as Metal Knight, is an extremely cautious and technologically advanced character who gathers information about the Hero Association. Because Saitama repeatedly appears at the center of major battles and performs increasingly impossible feats, such as defeating the doctor’s robot enforcers, Bofoi understood that Saitama possesses incredible power. Bofoi doesn’t exactly come out and say he knows that Saitama's laissez-faire attitude isn’t a true impression of who he really is. Instead, he files that information for later use and continues to be obsessed with the one-punch man. Dr. Kuseno Dr. Kuseno's knowledge of Saitama is a little different from characters such as Genos or Dr. Genus. The anime has not given Dr. Kuseno a clear moment where he discovers or fully understands Saitama's secret, as he is primarily connected to Saitama through Genos. After Genos becomes Saitama's disciple, he frequently talks about his master and his incredible abilities. Kuseno, therefore, has plenty of reason to know that Saitama is extraordinarily powerful, especially as Genos continues to sing Saitama’s praises. Suiryu Suiryu first encounters Saitama when the latter enters the Super Fight Tournament disguised as Charanko. Because Saitama looks completely ordinary and is pretending to be a martial artist, Suiryu initially has no reason to take him seriously. However, Saitama's performance becomes baffling when he defeats Zakko with a single slap. When the martial artists eat the monster cell and transform into monsters, Saitama saves Suiryu from Bakuzan. Suiryu, who is at this point awed by the one-punch man’s strength, asks to be his apprentice, to which he declines. Turns out he has his hands full with Genos. Fubuki When Fubuki first meets Saitama, she initially sees him as an easy target for her Blizzard Group. His low B-Class rank makes her assume that he is nowhere near the level of the top heroes. However, Saitama makes it clear that he isn't interested in joining her organization, an answer she was not pleased to hear, and so she resorted to what she knows best: violence. Even as Fubuki gathered strong winds and hoped to shred Saitama to pieces, the hero was unharmed. He easily bested her, leading her to realize that Saitama isn't the insignificant hero his ranking suggests. She eventually witnesses enough of his abilities to understand that his strength is extraordinary, especially when she sees the powerful heroes who are constantly hanging out in his apartment. King King’s storyline in One-Punch Man can be seen in two ways: tragic and funny. For many, King is the strongest person on Earth due to the many monsters he has defeated. However, it turns out the “powerful hero” wasn’t actually the one who was fighting those monsters; he just happened to be there when Saitama was. The fact that King oozes cool way more than Saitama led the Hero Association to assume that he was the hero. King’s discovery of Saitama’s secret is interesting in that he pieces it together through all the times he was there during those fights. Their dynamic presents an intriguing dichotomy because the supposedly terrifying strongest man on Earth is actually powerless, while the low-ranked hero everyone underestimates is capable of defeating almost anyone with one punch. Mumen Rider During the Deep Sea King arc, several heroes try to defeat the monster, and he ultimately proves no match for them. When Saitama arrives at the scene, Mumen Rider is trying to fight a fight he cannot win and is rendered unconscious. While Mumen Rider is out, the one-punch man bests the Deep Sea King, but Mumen doesn’t witness this event. Saitama also deliberately allows the crowd to believe that the Deep Sea King was weakened by the other heroes, protecting their reputations rather than taking all the credit. That moment gives Mumen Rider a strong reason to respect Saitama, but it is important to distinguish that he didn’t exactly know then that Saitama was all-powerful; he merely suspected that a person who could defeat the evil monster was not ordinary. Bang When One-Punch Man begins, Saitama is friendless, lonely, and bored. However, he eventually begins collecting friends like Infinity Stones, with Bang being one of them. As Saitama continues to flex his hero muscles, he faces an opponent that is neither man nor monster when he has to stop a meteor from destroying his city. With his signature one-punch move, the hero succeeds in stopping the meteor from causing a doomsday catastrophe, an event that Bang witnesses and henceforth concludes that Saitama isn’t one to trifle with. When Saitama defeats Centichoro with a single punch, Bang is among the heroes who see the incredible result, giving him undeniable evidence that Saitama's actual abilities are vastly beyond his Hero Association ranking. As a martial-arts master who has spent his life studying strength and combat, Bang is better equipped than most heroes to recognize just how unusual Saitama is.