Kaijin is a word in the Japanese language that means a strange, mysterious, legendary, or mythical humanoid (human-like) creature.

Kaijins are human-like beings considered strange or mysterious because they have unusual, fantastical, or supernatural characteristics, abilities, or powers that make them different from regular humans.

The popular terms in modern-day English language usage that closely approximate the meaning of Kaijin are humanoid monsters, such as Bigfoot, and superhuman beings, such as Spiderman.


In cryptozoology, the term cryptid refers to any creature that some people believe exists based on anecdotal evidence but remains unsubstantiated by science.

Human-like or humanoid cryptids are known as crypto-hominids.

Crypto-hominids may be species, such as Neanderthals or Australopithecus, that have gone extinct but which some people believe still exist. However, scientists do not acknowledge the claims that they exist today because believers can’t show evidence that meets scientific standards.

Kaijin as humanoid monsters

Humanoid monsters are crypto-hominids that do not match any species recognized or described in the Linnaean taxonomic system for classifying biological organisms.

Such creatures are fictional or fantastical creatures corresponding to the Japanese term Kaijin.

Thus, humanoid monsters such as Bigfoot, Yeti, the Minnesota Iceman, reptilian humanoids, werewolves, dogmen, mermaids, melonheads, and other human-like monsters are all Kaijin.

Kaijin as superhuman beings

Superhero characters, such as Superman, Wonder Woman, Spiderman, Thor, Hulk, the mutant X-men, and other imaginary beings from the Marvel and DC Comics universes are Kaijin in Japanese usage because they are fictional human-like creatures with fantastical or supernatural powers.

Their superpowers make them superior or more powerful than regular humans.

Sightings and Tales

Origin of the Kaijin concept

Historically, the first reference to the Kaijin in Japanese literature goes back to the Edo Period of the Tokugawa shogunate (1603-1867) when a Kaijin reportedly washed ashore near Nagasaki.

The Yamato Honzo

According to the Japanese Encyclopedia of materia medica, the Yamato Honzo by Kaibara Ekken (1709), the Kaijin was a humanoid creature from the sea that looked like a normal human being.

It had normal-looking sense organs (eyes, ears, and nose) but webbed hands and feet modified for aquatic life. It also had skin-like tissues or folds of skin that hung from its waist and covered the lower half of its body like a trouser or hakama.

The sea Kaijin could survive on dry land for only a few days. It needed to return frequently to the sea to replenish its strength. The Kaijin refused to eat or drink the food that humans offered it.

Although it did not speak any human language, people believed it was an intelligent being. The Kaijin could not communicate because it didn’t speak or understand any known human language.

Scholars believe other literary sources, such as the Honzokomoku Keimo, published in 1803, took their information about the Kaijin from the Yamato Honzo.

Some sources described a sea woman with flaps of skin hanging down her waist like a hofuku (a kind of clothing).

The Kaijin in pop culture

The concept of the Kaijin goes back to the Edo period. However Japanese literature and movies in the 20th century adopted and adapted it to modern pop culture.

Japanese novels from the late 1930s introduced the supervillain as a Kaijin.

In the novel The Fiend with Twenty Faces (1936), Edogawa Ranpo’s Sherlock Holmes-like master sleuth Kogoro Akechi confronts a Kaijin (supervillain or fiend) master of disguise.

The term evolved in the post-World War II era to include characters in a new fiction genre featuring superhuman heroes and villains.

Kaijin vs. Kaiju

Kaiju means “strange beast” in the Japanese language. A Kaiju is a strange, mysterious, fictional, legendary, or mythical beast.

The Kaiju are different from the Kaijin primarily because they are monster-beasts rather than human-like or humanoid creatures.

Thus, strange fictional creatures and monsters such as Godzilla, Gamera, Rodan, Mothra, King Kong, King Ghidorah, and Mechagodzilla are Kaiju because they are not human-like.

Giant Kaiju, such as Godzilla, are also called Daikaiju. The word Daikaiju means “big strange beast.”

However, human-like characters such as H-Man and Human Vapor are Kaijin. Some define a Kaijin as a Kaiju with human-like characteristics.

Modern Japanese fiction and movies also have the animal Kaijin.

These are animals with human-like characteristics. Although they have animal appearances, they have powers of speech, human reason, and intelligence.


According to some skeptics, the Kaijin that reportedly washed ashore near Nagasaki City on Kyushu Island was, in fact, a sea lion or seal.

Sea lions and seals are marine mammals known as Pinnipeds (clade Pinnipedia).

Although many think they are the same, marine biologists distinguish them.

Sea lions

Seal lions are members of the clade Pinnipedia that belong to the family Otariidae.

Members of the family have long and muscular foreflippers. They use the flippers to support their upper bodies on land. They walk awkwardly with their front flippers and hind flippers.

The hind flippers are smaller than the front flippers. Sea lions use their hind flippers to aid walking by rotating them under their bodies.

They have short but thick body hair, well-developed upper bodies, and external ear flaps. They have brown bodies and make a loud “barking” sound.


Seals are members of the clade Pinnipedia that belong to the family Phocidae.

Seals tend to be smaller than sea lions and have streamlined bodies better suited for swimming than sea lions.

[Note: The fur seal is not a “true” seal. Marine biologists believe it is more closely related to sea lions than seals. Thus, they classify it alongside sea lions in the family Otariidae.]

You may distinguish seals from sea lions by observing the foreflippers. Seals have much smaller front flippers than sea lions. The webbed flippers ending in claws are too small and weak to support their bodies on land. Thus, seals tend to wriggle on their bellies when out of water.

Seals also don’t have visible ear flaps or external ears like sea lions. They only have tiny holes on the sides of their heads.

While sea lions are noisy creatures that make loud barking sounds, seals are quieter.

Other Name/sMonster-man, Hairen (Chinese), Sea monster, Sea human
TypeHumanoid, Monster
HabitatCities, Human Society, Ocean


https://yokai.com/kaijin/, “Yokai: Kaijin,” accessed on March 30, 2023.

https://sf-encyclopedia.com/entry/kaiju, “Encyclopedia of Science Fiction: Kaijin,” accessed on March 30, 2023.

https://www.nihongomaster.com/japanese/dictionary/word/18895/kaijin-%E6%80%AA%E4%BA%BA-%E3%81%8B%E3%81%84%E3%81%98%E3%82%93, “Japanese Dictionary: Kaijin,” accessed on March 30, 2023.

https://jisho.org/word/518696a1d5dda7b2c60445dd, “Kaijin (cryptid),” ​accessed on March 30, 2023.

https://maserpatrol.wordpress.com/2017/01/08/%E6%80%AA%E7%8D%A3-or-%E5%A4%96%E7%8D%A3-kaiju-or-gaiju/, “Master Patrol,” accessed on March 30, 2023.

https://oceanservice.noaa.gov/facts/seal-sealion.html#:~:text=Sea%20lions%2C%20on%20the%20other,and%20underneath%20their%20big%20bodies., “What’s the difference between seals and sea lions?” accessed on March 30, 2023.

https://academic.oup.com/chicago-scholarship-online/book/17574/chapter-abstract/175184182?redirectedFrom=fulltext, “The First Japanese Encyclopedias of Nature: Yamato honzō and Shobutsu ruisan,” accessed on March 30, 2023.

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