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One Punch Man is one of the most celebrated anime and manga shonen series in recent years, and, beyond the animation of the adaptation or the quality of the fighting scenes, its success lies mainly down to its premise: What happens when the protagonist has achieved ultimate power?
This is a premise that subverts a lot of common tropes in both shonen manga and superhero comics (the two biggest influences of the series): it deprives the protagonist of any potential growth in terms of power scaling and it makes any threat he can have borderline meaningless. This is how we are introduced to our protagonist, Saitama, a very simple and reserved guy that became so ridiculously powerful that even intergalactic tyrants can’t put a dent on him.
A common comment made by a person that hasn’t read the manga or watched the anime series is “So… he can beat anyone with just one punch? Doesn’t that get old very quickly?” This comment, however, does have some valid arguments. Why does Saitama work as a protagonist? Why are his fights never boring? What makes this premise work so well?
I already explained a bit of this in my flat character arc article, but it’s worth focusing solely on Saitama since he is one of the most noticeable examples when it comes to this approach in storytelling. I’m going to try to do this analysis without giving any potential spoilers to the reader, so let’s begin!
Changing The World Around Him

A common conception made by a lot of people is that character development is absolutely necessary for a story to work. And while that is fundamentally true, it is also worth pointing out that a protagonist doesn’t have to change, but rather change the world around him or her.
One Punch Man is a textbook example of the flat character arc: Saitama already had his development arc before the actual story. He had the event that turned him into a superhero and the training he went through to become this powerful. By the time the manga begins, he has reached his peak as a fighter and no one can match him.
This is very interesting because this series obviously plays around with many tropes in manga and comics. Saitama has been compared to and viewed as a satirical version of the likes of Dragon Ball’s Goku and DC Comics’ Superman and you can find elements of both in him. But he is not eagerly searching for strong rivals to fight against like Goku (even if he craves a great fight) and he is not saving people every day like Superman (even if he does from time to time).
Saitama is part of a world that feels a lot faster than himself and a lot of events that happen in the story are subtly impacted by him and it goes growing from there. Despite his strength, he is not a known hero and most people think he is a joke, which only adds to the comedic elements of the story and it serves as a nice contrast between his power and how he is portrayed.
He is also, in a way, nonchalant about his everyday activities and has lost hope of finding a strong opponent to fight against. This is why his real impact is not connected to what happens within him, but rather to the outside world.

So, when the story begins and Saitama starts defeating a lot of strong opponents with ease, things begin to unfold. While I enjoy Saitama quite a lot, what I like the most about One Punch Man is how different the rest of the cast is when compared to him–they can lose, they can die, they can improve and they can even have existential crises. All of that is allowed thanks to the actions that Saitama does and how that influences the entire plot.
As the story progresses, we see more and more of his impact. I’m not going to give spoilers about it, but some characters go to extreme lengths due to the actions and achievements that Saitama gets because of his strength, thus cementing how relevant and effective he is to the story as a whole.
This is something that a lot of people that consume stories don’t get, but that is why characters like Sherlock Holmes, Conan the Barbarian, Batman, and many more can remain interesting and effective even after decades of their creations: because their role isn’t to change within, but rather change the world around them. Saitama is just like that.
The Importance Of The Cast
Now, having said all that, it is also worth pointing out how a strong supporting cast complements a protagonist that has a flat character arc. For example, I have gone on record saying that the first protagonist of JoJo’s Bizarre Adventure, Jonathan Joestar, had a serviceable role in the first part of the series, Phantom Blood, but struggled because the supporting cast didn’t elevate him and the exact opposite happens in One Punch Man.
The cast in One Punch Man is rich, filled with characters with a lot of personalities and with their own motivations and agency, thus making the story feel vast, enjoyable, and with a lot of angles to stay interested. This is something that we see in series like Hunter X Hunter, where the protagonist is not the center of this universe and there are a lot of things going on at the same time.
Therefore, Saitama also benefits from the setup that the creator has established, with a protagonist that reacts to a lot of events that the other characters cause and puts his own spin on the situation. This is phenomenal because it makes the world feel a lot more realistic and there are a lot of great subplots that don’t feature Saitama at all and they are some of the best in the series.
This is a protagonist that is very straightforward, very well-written, and does his job well, which allows for a lot of interesting concepts to be explored during the series. One Punch Man is a brilliant series because it knows what it is and how they work, thus adding a lot of value and maintaining a degree of interest as one of the best manga and anime franchises of the last decade.