Mysterious Beings

No shared silhouette links these creatures, since their bodies form through countless different routes. Some run on machinery close to human biology, drawing in oxygen and giving off carbon dioxide, while others work by means nobody can explain. Evil Natural Water, for instance, shows only its eyes as visible organs yet somehow steers an entirely liquid body.

Certain monsters, or pieces of them, turn out to be edible for exceptionally powerful people. Saitama once stripped Kombu Infinity of its leaves to simmer a broth and suffered no ill effects, and Garou chewed the arm of a foe he had just felled without any trouble, although a normal person would not likely walk away so unharmed.

Their reasons for turning on humanity cover a wide spread. A few, like Piggy Bancon and Tongue Stretcher, amount to little more than public nuisances; others such as Crablante and Surprise-Attack Plum lash out from revenge; whole clans like the Seafolk and the Subterranean People covet the surface world for themselves; and the most extreme, Vaccine Man and Homeless Emperor among them, chase the outright erasure of the human race.

Their numbers cluster heavily around Z-City and Q-City. Despite an instinct toward reckless, impulsive behavior, they can still band together, a fact proven by the Monster Association, which formed to rival the heroes and sow chaos. Monsters even sense one another's distinctive auras, which is how so many streamed toward Z-City to enlist.

Dr. Genus explains that a person can slip into monsterhood alone, driven by a craving to become something else, a private complex, or a swell of discontent that sparks abnormal cell activity and remakes the body around the fixation. A crab glutton turned into Crablante, and Devil Long Hair's obsession granted his monstrous form control over his own hair. Swallowing a Monster Cell offers a shortcut that amplifies strength and talent, though it freezes any further growth and, by Choze's account, secretes a brain chemical that strips away the user's morals.

Science can also build monsters outright, as with Marugori, while pollution or genetic tampering twists ordinary animals into them, as seen with TurtleBerus and Shiverhuahua. Still others simply belong to hostile non-human lineages, whether the vampire bloodline behind Pureblood or the alien origins of Boros. The Association gauges each threat with Disaster Levels, climbing from Wolf through Tiger, Demon, and Dragon up to God, with a Dragon-or-higher tier wedged near the top and rare below-Wolf or unknown labels at the margins. Ratings weigh how aggressive a being is, how hard it is to put down, and its raw fighting power.

The steady rise of such creatures over roughly the past fifteen years is exactly why Agoni founded the Hero Association. In more recent times, Sweet Mask notes that highly intelligent monsters, once a rare sight, now surface often and mostly arise from humans themselves.