One-Punch Man is an anime all about superheroes fighting monsters, and it boasts a host of characters that could even give My Hero Academia‘s All-Might a challenge. Power levels aside though, the series is full of side characters who are interesting beyond their physical capabilities.
The premise of the show is a bit of a joke in and of itself, therefore many of the heroes have bizarre or silly gimmicks and personalities that make them appealing to anime fans everywhere. There are some that function more as a one-off gag, and others that tie into the plot in unique and interesting ways.
Metal Knight
Metal Knight defeats monsters with Iron Man-style combative technology that rivals Genos’ own. There’s an interesting twist that this ‘hero’ is in fact a remote-controlled drone, with the mysterious and elusive pilot controlling it from a hidden location.
When interacting with other heroes he has the personality of a cold, calculating scientist, treating every encounter more as an experiment than a battle to save people. He’s an intriguing presence that everyone seems to both respect and fear.
Terrible Tornado
Terrible Tornado is the older of the psychic sisters and one of the most powerful Class-S heroes, ranking second in the association. Similar to Saitama, she has a bored, lackadaisical attitude because of the fact that she can win almost any fight easily with her esper powers.
However, unlike Saitama, Terrible Tornado is a bit nastier. In season 1 she steps up to fight off the incoming alien invasion, berating fellow heroes along the way. And, when she’s forced to intervene in order to protect her sister in season 2, she seems more annoyed and inconvenienced than anything.
Speed-o-Sound Sonic
Not exactly a hero or villain, Speed-o’-Sound Sonic is a rogue element all his own. He has no flowery motivations or elaborate plans, instead, his only goal is simple; to defeat Saitama for humiliating him.
This self-proclaimed rival of Saitama is a formidable force to be sure, as he’s even able to hold his own against Genos in season 2 with his super speed allowing him to appear in multiple places at once. Anime fans will have to wait and see where this character goes, as in season 2 he eats a monster cell provided to him in order to become more powerful to defeat Saitama.
Suiryu
Everyone in One-Punch Man has their own motive for getting stronger. Suiryu’s is that he just wants to be powerful enough to be left alone and live comfortably. As the head honcho and prospective champion of a martial arts tournament, he brings a relaxed energy that rivals Saitama’s, though he turns out to be a sore loser, getting a bit too high on his own fumes.
He makes for an entertaining matchup with Saitama, as he’s humbled by being unable to affect him at all with his physical prowess. Even after his defeat, he plays a pivotal role in the plot, standing up to Goketsu as he tempts martial artists with monstrous enhancements.
Watchdog Man
Among Class-S’ heroes is a man who wears a dog costume by the name of Watchdog Man. This character is more of a visual gag, but an entertaining one. Amusingly, for most of this series his power is only implied, with still images of him sitting dog-style atop a pile of defeated monsters. It’s not until season 2 when Garou challenges him that he’s even seen in action.
He fights by dodging around on all fours and does it all with a perpetual deadpan expression on his face. He is in fact so powerful that Garou cannot defeat him, and he later incorporates Watchdog Man’s four-legged fighting style into his repertoire.
Metal Bat
With his pompadour and jacket, Metal Bat has the aesthetic of a Japanese high school punk. At first glance his gimmick is amusingly simple; he has a metal bat and he will hit hard with it–hard enough to be considered Class-S.
In season 2, however, a bit more is revealed, as he is apparently able to become more powerful as he takes more damage, attributing this to his ‘fighting spirit.’ Additionally, it’s revealed that he has a softer side when it comes to his little sister, as he’s vowed to never fight in her presence at her behest.
Hellish Blizzard
At the top of B-Class is Hellish Blizzard, a woman with powerful esper abilities and the younger of the psychic sisters. She is an interesting semi-antagonistic force throughout the show. She presents as a hero and is registered with the association, but she is motivated entirely by the ranking system and maintaining hers as a point of status. To this end, she stakes her position and employs a mob of goons to prevent other heroes below her from rising up past her.
Despite her less than heroic motives, she does come through at a key moment in season 2, stepping in to fight members of the Monster Association who rise up to attack the city. Though, she does have to be bailed out by her older sister.
Silver Fang
This character could be described as a more serious take on Master Roshi from Dragon Ball Z. Despite his unassuming appearance as an old man, Bang, or Silver Fang as he’s known by the association, is a Class-S martial artist hero.
In season 1 he takes an amusing role as a mentor figure, especially because it’s for someone who may not even need mentorship (Saitama). In season 2 he makes for some interesting drama, being the one who trained Garou, season 2’s main antagonist and aspiring monster. His intense fighting style makes him a match for his protege, despite his age.
King
This Class-S Hero is teased throughout season 1, and it isn’t until season 2 that his status as a hero is revealed to be a farce. The whole time he’s been ranking up by unintentionally being present after some other hero has defeated a monster, getting credit for saving the day. Even his ‘King Engine’ is just his heart pounding so loud from the stress of an imposing monster.
What’s more is King owes his ‘hero’ origin to Saitama himself, having been saved by him while receiving his characteristic scar in the same encounter. The two have developed an amusing casual relationship as gamer-bros, and King himself even has true moments of heroism, drawing on his experience reading manga and playing video games.
Mumen Rider
What makes Mumen Rider a great side character is that he is the opposite of Saitama in a lot of ways. Where Saitama became obsessed with being strong and beating monsters in fights, Mumen Rider is focused on helping people as best he can. And where Saitama grows frustrated with his own power level and inability to engage in a fight that challenges him, Mumen Rider perseveres and continues to be a hero despite his lack of power.
In one of the most iconic character moments in the series, when Saitama finally shows up to fight Deep Sea King after Mumen Rider’s taken a beating, there’s a moment of respect as the baton is passed. The hero-for-fun picks up where the true hero left off. In season 2 he intervenes to prevent fellow heroes like Tank Top Master from going too far, and stands up to monsters attacking a hospital even while injured. In spite of his physical weakness, Mumen Rider has the heart of a true hero.
