The Giant Meteor Arc is the sixth arc of the series, and the third arc of the Hero Association Saga.
Genos reads out the news that Saitama went from last to the 342th place. Saitama is not impressed by it and asks what Genos has been doing. Genos explains that he ranked 17th, but 6th in popular votes, much to Saitama's shock. Genos reads, without embarrassment, some commentaries of others about him that wrote their impressions after looking at one picture of him. Despite that, Genos exclaims that he has yet to meet someone as astounding as his teacher, to which Saitama is creeped about it. While they are talking, miles above them near Earth, a giant meteor is on impact route towards the planet. Genos is called to go the Hero Association for some unknown reason. Genos arrives at the Z-City Branch, with a suitcase, where he meets Bang. Genos recognizes Bang as the 3rd ranked S-Class hero. Bang explains that everyone from the Hero Association evacuated, as all S-Class heroes were called to go there, and they are the only two remaining. Genos wonders why, which Bang continues to explain that everyone is preoccupied or didn't bother, since they were ordered by the Hero Association for an unreasonable Dragon level disaster task. Bang was ordered to stop the impact of the meteor, which could wipe out Z-City, and by protecting the people from the meteor will make the Hero Association's name rise.
However, Bang claims it impossible, and advise Genos to evacuate. Genos still stays and asks if the citizens were informed. Bang explains that half an hour ago, they that tried to estimate the point of impact and will announce an evacuation notice. Despite all that, Bang shows a fearless expression of the coming panic. The alarm signals, and Genos wonders what Bang is going to do. Bang is going to stay and is going to protect his dojo with his Rock-Smashing Water Streaming Fist. As he turns around, he notices Genos already left the building. Above them the meteor destroys a satellite near orbit, heading closer to the Earth.
The warning signal to evacuate, shocked the citizens and are left without hope. Genos leaps from rooftops and notes that the meteor will also destroy the outskirts of Z-City. He decides to test his prototype, and activates his suitcase which shows the words "Arms Mode". He throws the suitcase in the air, which forms into a set pair of arms and attaches it to his arms and lands on a rooftop nearby the point of impact. Genos wonders if he can do some damage with his incineration cannons and hopes to protect his teacher. As he prepares himself, a huge robot flies above him towards the point of impact of the meteor.
The mechanical robot flies towards a building and lands on it. Genos approaches the robot and wonders if it is Bofoi.
Genos pleads for Bofoi's assistance in destroying the meteor, but Bofoi refuses, stating that the only reason he is there is to test out a new weapon system. Bofoi then goes on to reveal that what Genos is talking to is just a remote controlled robot and that his real body is a safe distance away from the imminent impact site and he would rather be called by his hero name "Metal Knight." At that point the meteor roars closer and Genos jumps off to another building. He has calculated to be the point of impact, as he is doing this, Bofoi lets off a volley of large missiles which hit the meteor, cause a large explosion but doesn't stop the meteor at all.
Genos' mind starts racing about how to destroy the meteor when Bang shows up and calms him down. A picture of Saitama runs through Genos' head and he rips his hoodie off and opens his chest plate revealing a 'core' which he then pulls out and attaches into the bicep of his left arm. He then tells Bang to get down and launches a massive attack at the meteor. Genos attack proves too little to stop the meteor and he drains himself of energy and falls to the ground. At this point, Saitama shows up and asks Bang to take care of Genos and then promptly launches himself headlong towards the meteor. He quickly arrives at the meteor and punches himself through it, the meteor cracking up and exploding in his wake.
The pieces of the meteor then start to rain on Z-City, destroying a bunch of buildings, including the one Genos and Bang are on. Saitama then lands, looks around, and nonchalantly walks away.
Three days after the Meteor incident Saitama and Genos are relaxing in their apartment watching the news about the devastation the meteor fragments caused. Genos states that if the Hero Association had asked Saitama to help in the first place then the damage would have been reduced. After a brief discussion, Genos reveals that the incident raised their hero rankings: Saitama went from Class-C rank 342 to rank 5, Genos went from Class-S rank 17 to rank 16, and even Bofoi went up in rank from Class-S rank 7 to rank 6. Saitama is severely shocked by the jump in his position. After another brief discussion about Disaster Levels, Saitama decides to go for a walk.
As Saitama is walking around Z-City, taking note of the destruction, he is accosted by Tanktop Tiger. Tiger accuses Saitama of taking credit for the meteor incident that he did not deserve. Saitama blows off these accusations, which angers Tiger, who then calls out his brother. Tanktop Black Hole then makes his entrance and the two brothers then accuse Saitama of cheating again. Saitama seems rather put off by this and asks the two what they plan on doing about it. Tiger starts to threaten Saitama with violence but is cut off by his brother who states that he knows the cruelest way to punish Saitama. Black Hole then takes a deep breath and in an extremely loud voice starts calling out Saitama, stating that he's to blame for the destruction of the town. As he goes on like this, citizens from the area start to gather on the group. Eventually, some of the citizens start to join in. At that point, Black Hole calls on Saitama to resign, which the citizens agree too.
As this is happening, Bang is watching nearby from the roof of a building. He expresses his disappointment in the citizens and states that he'd rather see Saitama resign from the Hero Association than to see him corrupted by it. At this point, Black Hole goes to make his "decisive" move. He acts shocked and acts like Saitama made a move to start attacking the citizens. He and Tiger then step forward and state that they will "protect" the citizens by taking Saitama down. At this point Bang leaves, stating that he'd rather not watch a "public execution." Tanktop Tiger then steps forward and challenges Saitama first.
He charges forward only to be casually knocked off into the distance by Saitama. Black Hole, enraged by this jumps forward and grabs Saitama's hands, only to fall to his knees due to the pain of having his hands being crushed by Saitama. He starts apologizing profusely, stating that he lied and that he gives up. Saitama interrupts him at this point, saying to everyone in the area that it was, in fact, his fault that the destruction was his fault and that if anyone had a problem with it that they should say it to his face. Someone tries to interrupt, but Saitama cuts him off stating that he is not a hero for the people's admiration, he does it because he feels like it. Several days later a Mysterious Being is seen walking up from the ocean.
- Saitama went from Class-C rank 342 to rank 5, Genos went from Class-S rank 17 to rank 16, and Bofoi went up in rank from Class-S rank 7 to rank 6.
- Bang learns of Saitama's strength and decides he wants to train him.