Read One Punch Man Manga Chapter 21

One Punch Man Manga Chapter 21 Summary

The Meteor Crisis

Saitama and Genos’ Hero Rankings

The chapter begins with a lighthearted scene as Genos reads the updated hero rankings. After starting at the very bottom, Saitama has climbed to 342nd place. While most heroes might celebrate such progress, Saitama is unimpressed, treating it as meaningless.

Meanwhile, Genos proudly reveals that he has ranked 17th overall and 6th in popularity. Citizens admire his mechanical appearance, leaving positive impressions based on nothing more than a picture. Genos accepts the praise with his usual seriousness but insists that no one could ever compare to his teacher, Saitama. This over-the-top admiration unsettles Saitama, adding comic relief before the story escalates.

A Deadly Threat Appears – The Meteor Approaches

As their conversation unfolds, a catastrophic event begins above Earth’s atmosphere: a colossal meteor hurtles toward Z-City. Its size and speed make it a Dragon-level disaster—one of the highest threat classifications in the Hero Association system.

Genos is suddenly summoned to the Z-City branch. There, he meets Bang (Silver Fang), the legendary S-Class Rank 3 hero. Bang explains that most S-Class heroes either ignored the call or were tied up with other threats, leaving only a handful available.

Bang admits that the mission—stopping a meteor capable of wiping out the entire city—is nearly impossible. He himself chooses to stay only to protect his dojo, calmly accepting the destruction that may come. But Genos, driven by determination and his devotion to Saitama, refuses to retreat. Instead, he prepares to fight.

Panic in Z-City

Alarms blare across Z-City as evacuation orders spread. Citizens flood the streets in chaos, realizing the hopelessness of their situation. Many despair, believing their homes and lives are already lost.

Among the chaos, Genos leaps across rooftops, his focus unwavering. He knows that even if he fails, his duty as a hero demands that he try. His loyalty to Saitama fuels him, pushing him to face overwhelming odds without hesitation.

Genos Activates Arms Mode

Arriving at the estimated point of impact, Genos unveils a new upgrade. Tossing his suitcase into the air, it transforms into mechanical arms that fuse seamlessly with his own—a weapon system labeled “Arms Mode.” Armed with his enhanced incineration cannons, he sets his sights on the falling meteor.

But Genos isn’t alone. A massive robotic unit suddenly soars overhead and lands nearby. Genos recognizes it as the work of Bofoi, also known as Metal Knight, another S-Class hero.

Metal Knight’s True Intentions

Genos quickly pleads for Metal Knight’s help in stopping the meteor. However, Metal Knight coldly rejects the idea of cooperation. He reveals that the giant machine Genos is speaking to is only a remote-controlled unit, while his real body remains far from danger. His true motive? To use the meteor strike as a test for his new weapon system.

Despite his detachment, Metal Knight unleashes a powerful missile barrage at the meteor. The explosions rock the skies, yet the meteor remains intact, descending ever closer.

Genos’ Desperate Attack

Realizing the threat is greater than expected, Genos pushes himself to the limit. Guided by memories of his teacher, he rips open his chest plate, extracts his core, and integrates it into his arm to unleash maximum power.

With a deafening blast, Genos fires his most destructive incineration attack at the meteor. The impact shakes the city and splits part of the meteor’s surface, but it is still not enough. The meteor continues to descend, unstoppable.

Drained of energy and battered from the effort, Genos collapses onto the ground. His willpower was unmatched, but his strength fell short against nature’s fury.

Saitama’s Arrival and the One Punch Solution

At the height of the crisis, Saitama finally steps in. Calm as ever, he tells Bang to look after Genos. Then, without hesitation, he launches himself skyward toward the meteor.

With one effortless punch, Saitama shatters the enormous rock into countless fragments. The meteor disintegrates under his fist, but the aftermath is bittersweet. The fragments rain down on Z-City, crushing buildings and leveling entire districts.

Still, the complete annihilation of Z-City is avoided—thanks solely to Saitama’s intervention.

Aftermath – A Hero Without Recognition

As the dust settles, destruction surrounds the heroes. Entire neighborhoods lie in ruins, and citizens stare in shock at the devastation. While Saitama’s intervention saved them from extinction, many are left with mixed feelings. To them, the “hero” who destroyed the meteor also caused massive collateral damage.

True to his nature, Saitama doesn’t seek thanks or glory. He lands quietly, surveys the ruins, and walks away without a word—once again embodying the idea that true heroism is selfless, even when it goes unnoticed.

Themes and Takeaways from Chapter 21

• The Nature of Heroism – Genos demonstrates the struggle of a hero who fights despite the odds, while Saitama shows that true strength often goes unappreciated.
• Sacrifice and Collateral Damage – Even victory comes at a cost, as Z-City’s partial destruction raises questions about whether the end justifies the means.
• Recognition vs. Reality – Genos craves acknowledgment, while Saitama is indifferent, highlighting the contrast between public opinion and true heroism.
• The Limits of Technology – Metal Knight treats the disaster as an experiment, revealing the cold, detached side of some heroes compared to Saitama’s selfless approach.