The Japanese manga series One-Punch Man contains a number of fictional characters created by One and illustrated by Yusuke Murata. The series follows a superhero named Saitama and his disciple Genos who join the Hero Association so they can be recognized as such when they fight various monsters and supervillains. The Hero Association ranks all of its members by a Class and a ranking within that class. Characters listed are ones noted by the author in the manga profiles, ones that were highlighted in the anime character list, and ones that recur over several story arcs.
Main characters
Saitama
The title protagonist, , is a bald-headed 25-year-old man who is bored of fighting because he is able to effortlessly defeat enemies with a single punch. He lives in an apartment in City Z. Three years prior to the start of the series, when he still had hair, Saitama was job hunting when he defeated the powerful supervillain Crablante that attempted to kill a child with a butt-chin. Saitama says he became a hero "for the fun of it". His abilities mainly consist of physical abilities magnified to an immeasurable degree: strength is the true power of Saitama, with speed, stamina, and durability being mere side-effects. He attributes this to a daily training regimen like 100 push-ups, 100 sit-ups, 100 squats, a 10 km run, eating healthy food, and abstaining from use of the air conditioner or heater in order to reinforce his mental fortitude. He also mentions training even when his body was wounded and made strange cracking sounds. Three years of this spartan training pushed Saitama to his limits, making him evidently unbeatable. Early in the series, he picks up a disciple and roommate, Genos.
Though he had broken all the physical records in the Hero entrance exam by huge margins, Saitama enters the Hero Association with a score of 71, giving him one of the lowest ranks in the Hero Association. This is due to his miserable performance on the mental exam. He soon goes up the ranks by performing many deeds, although many of his efforts are not recognized because of collateral damage or higher-tiered superheroes receiving more credit. These include defeating the raging ninja supervillain/assassin known as Speed-o’-Sound Sonic (who became his unlikely rival) and destroying a meteor similar to Chicxulub, each with a single punch. As of the current arc of the webcomic by ONE, he is A-Class rank 39. Regardless of his rank, he does not mind giving others the credit, as demonstrated in his actions following the fight against the Deep Sea King. In the Dark Matter Thieves' story arc, he is unfazed by the telekinesis of a powerful esper, further displaying his resistance. This arc was also one of the only times he has used his "serious punch", defeating the world-conquering leader of the aliens, Lord Boros. It was also revealed that Saitama's power can continue to grow limitless as demonstrated during his fight with Cosmic Garou, with the latter leaving him behind on the power scaling through every blows exchanged. Through various circumstances, he forms friendships with Mumen Rider, Bang, King, Genos, and Blizzard. His superhero name in the association is .
Saitama is voiced by Makoto Furukawa in the original Japanese version and by Max Mittelman in the English dub.
Genos
is a 19-year-old cyborg who becomes Saitama’s disciple after bearing witness to Saitama’s easy victory over Mosquito Girl. Four years prior to the start of the storyline, his family was killed by a rampaging cyborg known as Mad Cyborg. Genos was nearly killed in the attack and his body was destroyed, so to keep him alive, a scientist named Dr. Kuseno took Genos in and modified his body to make him a cyborg with destructive capabilities. Ever since, Genos has been obsessively searching for traces of Mad Cyborg, vying vengeance. Immediately prior to the main story, Dr. Kuseno argues that Genos should move on from his obsession with Mad Cyborg, but Genos remains steadfastly convinced that justice demands the destruction of the cyborg. His perfect score on the entrance exam for the Hero Association places him in the highest class, S-Class, far above Saitama's placement in C-Class, but he still considers Saitama to be his master and goes with him whenever he is not summoned to other missions. Saitama often has to save him, as Genos' headstrong personality causes him to jump into action without thinking. He lives with Saitama after offering a sizable down payment for his share of the rent. His superhero name in the Hero Association is
Genos is voiced by Kaito Ishikawa in the original Japanese version and by Zach Aguilar in the English dub.