Every time a promising villain appears, Saitama beats the snot out of ’em with one punch! Can he finally find an opponent who can go toe-to-toe with him and give his life some meaning? Or is he doomed to a life of superpowered boredom?

Saitama’s easily taken out a number of monsters, including a crabby creature, a malicious mosquito girl and a muscly meathead. But his humdrum life takes a drastic turn when he meets Genos—a cyborg who wants to uncover the secret behind his strength!

For three years, Saitama has defeated countless monsters, but no one knows about him… That’s because he isn’t in the Hero Association’s registry! Together with Genos, Saitama decides to take the Hero Association’s test! But can they pass?!

Saitama is now a certified hero! And with that title comes great responsibility—he’s required to perform one heroic deed per week. While Saitama makes the rounds to meet his quota, an incoming threat from outer space is screeching toward Earth...

To stop a Demon-level crisis, Saitama and company head toward the action. However, even Class-S heroes prove to be no match for the Deep Sea King! In order to protect the good citizens, our heroes will need to summon all of their courage and confront this threat!

An emergency summons gathers Class S heroes at headquarters…and Saitama tags along. There, they learn that the great seer Shibabawa left the following prophecy: “The Earth is in danger!” What in the world is going to happen?!

When aliens invade Earth, a group of Class-S heroes finally finds a way to fight back and go on the offensive. Inside the enemy mother ship, Saitama fights Boros. Faced with the alien’s frightful power, he decides to get serious! What is the Earth’s fate?!

Class-S hero King is known as the strongest man on earth. Even monsters fear him. But when a mysterious organization sends an assassin after him, the shocking truth about King is revealed!

Time bomb Garo, a monster admirer, finally explodes, attacking the Hero Association! Meanwhile, Miss Blizzard visits Saitama at his apartment. Because of his lower rank, she plans to make him one of her subordinates, but…

Hero hunter Gato intensifies his onslaught, so of course Saitama decides now is the perfect time to join a combat tournament. Meanwhile, Class-S hero Metal Bat takes an assignment guarding a Hero Association executive and his son, and before long trouble appears!

While Saitama's distracted at a martial arts tournament, Centichoro, a threat-level Dragon monster, attacks! Metal Bat engages it in battle but struggles against its gargantuan size. The monster knocks him into the distance and right into the path of hero-hunter Garo! 

At the martial arts tournament, Suiryu of the Dark Body Art shows promise with his outstanding strength. But outside the stadium, a large number of monsters are pushing the heroes, even Genos, to their limits! Inside, unaware, Saitama approaches his match against Bakuzan!

The Class-A heroes struggle in their fight against the giant monster Multieyed Octopus. Wait, is that Class-S hero Flashy Flash joining the fight?! Unfazed, the Monster Association continues ramping up its attacks, but its goal remains a mystery. Meanwhile, the martial arts tournament reaches the semifinals!

The monster Goketsu appears at the martial arts tournament, and in an attempt to turn its participants into monsters, he gives them monster cells. Tournament champ Suiryu fights the newly monsterized fighters one after another, until a certain hero rushes to his side to help!

Despite just finishing a martial arts tournament and immediately dealing with the Monster Association invasion, Saitama still proves to be so incredibly strong that he feels empty inside. King lectures him on how to live like a hero, but it doesn’t help. Meanwhile, servants of the Monster Association close in on Speed-o’-Sound Sonic!

Surrounded by heroes, Garo finds himself in a tight spot. But despite the great numbers, he defeats the heroes one by one with his unmatched strength before Genos comes rushing in! Meanwhile, Saitama is reaching the height of irritation in his own battle…with King?!

The hero hunter is near death when the Monster Association attempts to steal him away, unleashing Centichoro in the process. Bang and company face it head-on before Genos boldly enters the fray!

Immediately before the big Monster Association battle, the Class-S heroes hold a strategy meeting. Unfortunately, they just aren’t in sync, and when Amai Mask barges in, the situation only gets worse. Thankfully, King appears just in time to boost their morale—and it’s a good thing, too, because suddenly the big monster battle begins!