A yōkai, or Japanese monster, shown in a scroll depicting the hyakki yagyō, or "night processional of 100 demons" Emaki Wacky / Wikimedia

The numbers don’t lie: When it comes to spending money on Halloween, the Japanese have nothing on Americans; consumers in the United States shell out $6.9 billion during the holiday, compared with ¥122 billion, or about $1 billion, in Japan. But the country that popularized costumed performance art like kabuki and cosplay does have a competitive edge in one realm: Perhaps no country loves—and hates, and fears, and imagines—monsters to the extent that Japan does.

In Japan, monsters—or really any otherworldly or inexplicable being—are known as yōkai. One of the first compilations of yōkai, the 18th-century Konjaku Gazu Zoku Hyakki (“Continued Illustrations of the Many Demons Past and Present”), contained 54 entries. Wikipedia lists almost 300 “legendary creatures from Japan,” including kamaitachi (a “slashing sickle-clawed weasel that haunts the mountains”), gashadokuro (“a giant skeleton that is the spirit of the unburied dead”), and tsurube-otoshi (“a monster that drops out of the tops of trees”). Yōkai have inspired at least two Internet databases.

According to Michael Dylan Foster, a scholar of Japanese folklore at Indiana University Bloomington, the origins of yōkai are diverse. Some yōkai aren’t strictly Japanese, but rather derivatives of Chinese legends or characters from Buddhist texts (like the oni, giant demons similar to ogres). Many first appeared in local tales and were incorporated into folklore when oral storytelling (setsuwa in Japan) was committed to writing. Like most folklore around the world, the yōkai reflected concerns in Japanese society—like fear of outsiders and the ambiguity of death—at the time they were conceived. There was the concept of the hyakki yagyō, or “night processional of 100 demons” invading the real world, and tales of yūrei, ghosts who’d failed to pass on and were prone to taking revenge on the living. Consider the story of the weeping stone, recounted in Ghost and the Japanese: Cultural Experience in Japanese Death Legends:

Along the path through the mountains near Sayo-no-Nakayama on Honshu, there is a stone that you can hear crying and complaining. A long time ago, people found a pregnant woman traveler dead and robbed on that spot. The murderer was never caught, and so the killing remains unresolved and unatoned for. The unlucky spirit of the dead woman could never find any rest, and finally took refuge in that stone. Every night she weeps because of her grief. You can still hear her crying.

Foster, writing to me by email (he was in Japan attending a symposium about yōkai), said the large number of yōkai in Japan doesn’t have “anything to do with there being more belief in the supernatural or in folkloric creatures in Japan than there is elsewhere.” Instead, he added, “it has to do with the way in which yōkai, at a fairly early stage, became a very lively part of popular culture (fiction, drama, illustrated texts, games, etc.).”

The tale of the weeping stone, depicted in a woodcut by Utagawa Hiroshige (Douggers / Wikimedia)

This integration into pop culture dates back to the Edo period of Japanese history between the 17th and 19th centuries. In Pandemonium and Parade: Japanese Monsters and the Culture of Yokai, Foster describes how chronicling the exploits of yōkai became a form of recreation, in part through telling ghost stories in an event called hyaku-monogatari, or “100 stories.” The storytellers would light 100 lanterns and extinguish one for each tale told, until their surroundings gave way to total darkness. At this point, a yōkai would supposedly appear among those in attendance.

The yōkai also took root through catalogs like Continued Illustrations of the Many Demons Past and Present, the oldest of which were written by a man named Toriyama Sekien. The catalogs included the name of each yōkai alongside a description, creating an encyclopedia of the mysterious. While most of Sekien’s monsters were taken from Japanese and, to a lesser extent, Chinese folklore, many were the author’s own inventions, according to Pandemonium and Parade. These beings tended to be categorized by where they could be found. One entry, about mōryō, a spirit that resided in Japan’s rivers and mountains, was thus described: “Its figure is like that of a three-year-old child. It is red and black in color. It has red eyes, long ears, and beautiful hair. It is said that it likes to eat the livers of dead bodies.”

Foster wrote that while “yōkai may be related to the animistic quality of Japanese religious systems,” their persistent popularity through the centuries is largely due to influential people and companies ensuring that the monsters continued to thrive “in the popular imagination.” Most of these people and companies have been Japanese; Shigeru Mizuki replicated the characters in manga comics such as the series GeGeGe no Kitarō and in a book of yōkai illustrations, while the filmmaker Hayao Miyazaki and writer Haruki Murakami have also promoted the imagery. Sometimes, yōkai have endured via urban legend. One legend that first spread in the late 1970s told of a creature who happened upon children walking home from school at dusk and asked, “Am I pretty?”—only to remove a white mask and reveal that her mouth was slit from ear to ear. She was known as kuchisake-onna, or “slit-mouthed woman,” and her purported existence made many children afraid to walk home.

Yōkai have thus remained a preeminently Japanese preoccupation, without the cross-cultural resonance of, say, werewolves and vampires, which are particularly popular in Europe but appear in the folklore of numerous civilizations, or the Loch Ness Monster, which, while Scottish, is well-known to people outside Scotland.

But yōkai have nevertheless, somewhat stealthily, gained prominence around the world through Japanese-made manga, television shows, and movies. Many of the Pokémon—short for “pocket monster”—that populate the multimedia juggernaut of the same name are based on yōkai. Nintendo is set to release the gaming phenomenon Yo-Kai Watch in North America. The horror movies The Ring and The Grudge are remakes of the Japanese films Ringu and Ju-On, respectively. The Grudge borrowed its ghosts—pale girls with long and disheveled black hair—from their mythical likenesses, the yūrei. Another forthcoming horror movie, The Forest, is based on Aokigahara, a forest near Mount Fuji that witnesses a high number of suicides and is said to be haunted.

Do Japanese themselves really believe in yōkai? “I think it is fair to say that when pressed on the question, most people do not believe in specific yōkai per se,” Foster told me, “but they might believe in the possibility of strange or unexplainable phenomena. … I think that some yōkai fit this sort of middle ground in which people want to believe in them, because of the excitement and possibility they represent, but know that there is no ‘scientific’ evidence to prove their existence.”

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