Saitama is a hero who only became a hero for fun. After three years of “special” training, though, he’s become so strong that he’s practically invincible. In fact, he’s too strong—even his mightiest opponents are taken out with a single punch, and it turns out that being devastatingly powerful is actually kind of a bore. With his passion for being a hero lost along with his hair, yet still faced with new enemies every day, how much longer can he keep it going?
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see all options Availability data: JustWatch
- Seasons
- 3
- Episodes aired
- 36
- Latest aired
- S03E12
- Total runtime
- 14h 24min
Timeline when each season aired
- Season 1 October 2015 – December 2015 12 episodes
- the show was away for 3 years and 3 months
- Season 2 April 2019 – July 2019 12 episodes
- the show was away for 6 years and 3 months
- Season 3 October 2025 – December 2025 12 episodes
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S01E01 The Strongest Man
October 5 · 24min find the promo
Show synopsis
Saitama is a guy who’s a hero for fun. After saving a child from certain death, he decided to become a hero and trained hard for three years. Though he’s now so strong he can defeat any opponent with a single punch, lately he feels as if, in exchange for overwhelming power, he’s lost something even more important.
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S01E02 The Lone Cyborg
October 12 · 24min find the promo
Show synopsis
A monster is moving toward City Z, one that has been created by the mysterious organization known as The House of Evolution. Genos, a young cyborg, attempts to stop it, but gets in over his head before Saitama happens along.
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S01E03 The Obsessive Scientist
October 19 · 24min find the promo
Show synopsis
Saitama and Genos glean information about The House of Evolution and its founder Dr. Genus, a scientist with dangerous ideas on artificial human evolution. Meanwhile, Dr. Genus learns of Saitama’s amazing strength and has plans of his own for One-Punch Man.
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S01E04 The Modern Ninja
October 26 · 24min find the promo
Show synopsis
A group of battlesuit-clad terrorists called “The Paradisers” appears in City F, led by an enormous man known as Hammerhead. Calling for the redistribution of wealth, the group targets the fat-cat Zeniru, who in turn dispatches his bodyguard to defeat them. Unfortunately, Saitama is on the same errand.
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S01E05 The Ultimate Master
November 2 · 24min find the promo
Show synopsis
Though he’s been doing the hero gig for three years, Saitama realizes that the public knows nothing about him. Determined to get a little recognition, he decides to become a pro hero, but first he must pass the Hero Association tests and become a full-fledged member.
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S01E06 The Terrifying City
November 9 · 24min find the promo
Show synopsis
It’s been five days since Saitama became a professional hero and he has yet to do anything heroic. When Genos informs him that C-class heroes who don’t fight bad guys are dropped from the hero registry after a week of inaction, Saitama heads out on patrol, yet can’t find any criminals or monsters to stop.
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S01E07 The Ultimate Disciple
November 16 · 24min find the promo
Show synopsis
An enormous meteor hurtles toward City Z, forcing the Hero Association to ask its S Class heroes to respond. When all their efforts prove in vain, Genos decides it’s up to him to protect the home of his master and stop the meteor, no matter what the cost.
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S01E08 The Deep Sea King
November 23 · 24min find the promo
Show synopsis
A pack of monsters calling themselves the “Clan of the Seafolk” arrive on the shores of City J intent on invading the land. When the hero sent to fight them is defeated easily by the Deep Sea King himself, Saitama and Genos head for the city to help.
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S01E09 Unyielding Justice
November 30 · 24min find the promo
Show synopsis
As the battle with the Deep Sea King reaches its climax, more heroes fall to the aquatic despot’s brutal attacks. Which of them has what it takes to be a true hero?
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S01E10 Unparalleled Peril
December 7 · 24min find the promo
Show synopsis
Saitama tags along to an emergency meeting of Class S heroes and discovers that a seer has foretold a serious danger threatening the Earth. Though the crisis could occur anytime in the next six months, the heroes are surprised to hear the roar of explosions that very hour!
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S01E11 The Dominator of the Universe
December 14 · 24min find the promo
Show synopsis
As a colossal spaceship floats in the skies above City A, a member of its monstrous crew battles on the ground against a group of S Class heroes. Despite their powers, they can’t seem to finish it off. Meanwhile, Saitama has boarded the enemy ship on his own.
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S01E12 The Strongest Hero
December 21 · 24min find the promo
Show synopsis
The inconceivably powerful Lord Boros has traveled untold distances in search of someone who can cure his boredom: Saitama! With the fate of humanity in the balance, will the two champions at last find in each other the worthy opponent they’ve been searching for?