Where Do Monsters Come From in One-Punch Man?

Monsters or mysterious beings in One-Punch Man are not a fully explained phenomenon. Regardless, there are several confirmed origins of monsterification.

Some monsters or Mysterious Beings have always existed, such as Vampires and Seafolk. Other monsters are artificially created, either through their own obsession or other means such as scientific manipulation. Both categories appear a lot more often in the last 15 years.

Let’s go over the different origins known to us below.

Natural One-Punch Man Monsters


Some monsters have simply always existed, such as the Seafolk, Skyfolk, and Vampires.

In an extra chapter in an early manga volume, it was stated that monsters (of all types) used to be a rare sight. When Saitama was in middle school, there was a nine-month period between the appearance of two monsters. News channels at the time picked up the trend of monsters showing up more and more often.

In the present day, we see natural monsters very often. All of my above examples, as well as others, have shown up very recently. Even so, natural monsters seem to be a minority lately, which is a clear indication that something is causing this change.

OPM Monsterification Through Obsession

Just like Saitama has become insanely strong due to his sheer determination, obsession can also lead humans to become monsters.

You have those that somewhat make sense, such as Fist Fight Djinn who transformed due to his obsession with fighting. Others are more questionable, such as a person who transformed into a monster because he shadowboxed too much with his ceiling light pull cord. Even wearing a costume too long such as Phoenix Man can trigger monsterification.

Still, people have always been obsessed with things such as fighting. It does not explain why there are suddenly so many more monster appearances. According to Dr. Genus, obsessed individuals begin their transformation when their environment triggers an abnormal cell reaction. The question remains why this reaction triggers now, while it did not before (or at least not nearly as often).

Biological Monsterification in One-Punch Man

Monsterification CellsEating uncooked cells of monsters can also cause monsterification. Monster King Orochi produces monster shells to transform others into monsters. This is not unique to just his cells though. It is more so that he is making use of a phenomenon that has always existed for his own purposes.

This phenomenon is not limited to just human beings, either. Some crows transform into monsters after they eat the remains of the Beast King. As a side note, these are NOT the crows that fight Suiryu, Snek, and Max. Those have been confirmed to be Gouketsu’s disciples, transformed through Orochi’s monster cells but lacking the willpower to keep their human senses.

Artificial Monsterification

Some monsterifications happen through Science. The most known example is Dr. Genus’ house of evolution, which had many monsters under its control. Similarly, it is also possible for robots and cyborgs to receive a threat level.

Natural disasters

Monsters also seem to be able to appear as the result of a natural disaster. Vaccine Man claims to be Mother Nature’s creation, a reaction to industrialization. His mission was to clear the earth of humanity so nature can prosper and further infections are prevented.

The Evolution of Mysterious Beings

We previously discussed how monsters are becoming an increasingly common phenomenon. Not only do they appear more and more often, but the average threat level also seems to be increasing.

Interestingly, Saitama seems to be attracting monsters. The Z city he lives in has even become abandoned due to monster activity. Watchdog Man’s Q City also suffers from a high monster concentration. Whatever the reason behind this is, we know that it is not a conscious one.  A monster seeing Saitama in action will often opt to flee after all.

As for an educated guess on what is causing this, we have to turn the webcomic. The below section contains spoilers, so proceed at your own peril. To see them, simply highlight this sentence and scroll down.

In the webcomic there is a being called God (spoiler image). It seems to be giving people monstrous powers behind the scenes. This being is capable of communicating with his subjects without being physically present. The only information we have about GOD is:

  • He is the one who gave Homeless Emperor his powers. He is also able to take back the powers he grants.
  • The energy balls he grants are confirmed to be related to those used by Choze and Vaccine Man. This only makes things more mysterious, as GOD did not directly turn them into monsters.

John Winkels

In recent years, the amount of series I watched and read has reached three digits. I love digging deep into different versions of the source material (anime, manga, light novels) and sharing the results with you.

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