Saitama is determined to become a superhero. After years of training he becomes strong and faces all sorts of monsters to protect humanity.
Genos is a cyborg who fights for justice. After having seen Saitama in action, he asks if he can become his student.
Hearing that Genos and Saitama are heading over to stop him, Doctor Genus releases his ultimate weapon -- a monster that even he can’t control.
The Paradisers are a group of men led by Hammerhead who want a world without work. Speed-o'-Sound Sonic confronts them and kills them all except one.
Genos and Saitama take the exam to become heroes. Saitama barely scrapes by, but Genos’s high scores attract the attention of the Hero Association.
The Hero Association detects intense mysterious activity in the ghost quarter of Z city and sends some of its members to resolve the matter.
Z city is threatened by a meteorite. The heroes of class S try to prevent a human catastrophe, but all their attempts seem to be in vain.
The Earth is threatened by the arrival of the abyssals from the sea. Various heroes try to stop them, but they are regularly defeated.
The king of the abyssals, after having defeated many heroes, seems really unbeatable. Fortunately, Saitama gets involved.
The heroes of class S are summoned to respond to a major threat: Shibabawa has foreseen a great danger set to occur some time in the next six months!
A creature leaves the alien spaceship which destroyed city A and attacks the heroes of class S. Saitama gets on board and kills most of the crew.
While the heroes are fighting hard against Melzargald, Saitama has to deal with the head of the aliens, the mighty Lord Boros, in an epic encounter.
While returning from shopping, Saitama and Genos spot King, a high-ranking hero who's the talk of the town. But King's hiding an embarrassing secret.
Garou wreaks havoc at the Hero Association. Meanwhile, the top member of class B tries to teach Saitama a political lesson, but gets a surprise.
After Bang kicks Charanko out of his dojo, Genos deduces that Garou's reappearance is behind this. Later, Garou goes up against the Tank Top gang.
The Hero Association takes steps to protect its executives. Saitama enters the tournament as Charanko but soon meets someone who could expose him.
After Garou's battle, two monsters invite him to join their association. Meanwhile, Saitama learns more about his fellow tournament participants.
Monsters around the tournament venue raise the possibility of an evacuation. Meanwhile, the medical staff is on standby for Saitama's next match.
The Class S Heroes fight rampaging monsters. Saitama punches his way into the final match, but his opponent Suiryu knows how to mess with his head.
Saitama's disqualification makes Suiryu the champion, but the celebrations are cut short when Gouketsu and his monsters crash the ceremony.
Bakuzan quickly recognizes his opponent and eagerly demonstrates his new powers. Suiryu tries to warn Saitama that he is facing certain death.
The Monster Association openly declares war on the Heroes and dares them to rescue their hostage Waganma. Word of the conflict reaches the public.
The poison slowly takes effect on Garou as he faces off against Death Gatling and the lower-ranking heroes. Tareo watches from the shack.
As Bang and Bomb beat on him, Garou recalls the real reason why he despises heroes and gains a second wind. Reinforcements soon arrive at his side.