Mysterious Beings



Mysterious Beings (怪人, Kaijin), or simply Monsters are terms used to refer to sentient creatures that terrorize the cities of the entire planet and pose a threat to society.

Overview
According to Dr. Genus, monsters are naturally created by an abnormal cell reaction triggered by negative emotions, other factors such as pollutants, enviromental changes and genetic engineering also are capable of creating monsters. Monsters first started appearing more frequently in the past 15 years. It is still unknown what their actual purpose is, but it seems that most of these creatures are hostile towards mankind, wreak havoc in the cities and terrorize the citizens. Some of the mysterious beings come from human backgrounds who were turned because of their obsession for certain things. For example, Crablante was turned into a Mysterious Being for eating too much crab or Fist Fight Djinn for his thirst for fighting. Furthermore, another alternative method for humans to be turned into Mysterious Beings is through the injection and absorption of Monster Cells provided by the Monster Association. In some case, a human can be turned into Mysterious Being in a bizarre manner like Jumping Spider is the result of the man who doesn't pull the spider out of his ear.

Mysterious Beings are especially concentrated in Z-City and Q-City. These beings are the reason the Hero Association was founded by Agoni.

Some Mysterious beings have created an organization similar to the Hero Association, possibly to fight them off, showing they can work together if they needed to. Mysterious Beings also seem to be able to detect the distinctive auras of other monsters as large numbers of monsters headed to Z-City to join the Monster Association.

Some certain Mysterious Beings or parts of their body can be edible for human like in the case of Saitama ripping all Kombu Infinity leaves to cook his Miso soup and he suffers no ill effects after that. Another example is Garou who ate a monster's arm to replenish his lost blood.

Types of Mysterious Beings
Natural Type: They are sentient races that have been dormant, living in seclusion from the surface world.
 * Seafolk: The Seafolk are a race of beings that have come from the sea to take the surface of the earth for themselves.
 * Skyfolk: The Skyfolk are a race of beings that have come from the sky to take the surface of the earth for themselves.
 * Subterranean People: The Subterranean People are the self-proclaimed "True People of the Earth". They live under the earth's crust, but grew too numerous in numbers and planned to take over the surface.
 * Terror Lizards: The Terror Lizards are dinosaur-like creatures that have come from mountains to take the surface of the earth for themselves.
 * Vampires: Ancient bloodsucking creatures with a long history.
 * Forest Tribe: A race of beings of unknown origin that have come to revive the lost greenery with fertilizer made of human corpses.

Unusual Type: The most bizarre type are the Mysterious Beings that were normal individuals whose change happened through performing an action obsessively.
 * Ugmons: Ugmons are grotesque creatures created from ugly humans.

Extraterrestrial Type: They are sentient beings beyond the planet Earth, coming from outer space. All members of the Dark Matter Thieves belong to this type.

Artificial Type: Normal beings or individuals which through scientific means gained superpowers or mutations. They can also be completely artificially created.
 * Mutants: Mutants are creatures created through genetic modification.
 * Robots: Robots with artificial intelligence that pose a threat to humans are treated as Mysterious Beings. G4 is a robot with artificial intelligence.
 * Cyborgs: Cyborgs are cybernetically enhanced living beings.

Humanoid Type: Mysterious Beings, which take on a humanoid form and are hard to distinguish from regular humans in terms of appearance. Do-S, Gale Wind, and Hellfire Flame are part of this type, although it is arguable for the latter two, since they were merely hiding their monster forms.

Non-Sapient: Some Mysterious beings are just feral animals, with no higher brain function, similar to that of a wild animal.

Disaster Levels
The attacks by Mysterious Beings have a scale on how destructive the attack is, which goes from Wolf level to God level. While created for ranking the threat of Mysterious Beings it's also applied to other elements that threatens human society such as the Giant Meteor. However, it should be noted these are the levels of how threatening they are to human society and thus don't truly represent their strength when compared to one another. As such some beings are stronger than the other while having the same disaster levels, such as the Armored Gorilla and the Deep Sea King. While both demon levels, the latter can defeat an S class hero while the former can't. Another example is that while both the transformed Gouketsu and Bakuzan are Dragon levels, the former can easily overpower the latter.

List of known Mysterious Beings
Dragons= Demons= Tigers= Wolves= Others=

Trivia

 * Despite being considered a God level threat by fans, during a Q&A section with the original author, it was stated that Boros is above Dragon. This could mean that Boros is in an unknown level between Dragon and God or indeed a God level threat, but it was still never specified.
 * Garou claims that he is a Disaster Level God. This hasn't been confirmed nor denied in the series yet.
 * Wolf is never used or even considered a disaster level in the anime.