Mar 25, 2024 I Brent Swancer

Mystery Beasts of Japan: Aquatic Apes, Mermaids, and Lake Monsters Edition

Japan has long been a mysterious land full of wonder, long history, and exotic beauty. Out past the fringes of the modern view of Japan as a place of bustling metropolises, there are huge expanses of wilderness, untouched wild places, and pristine sea sides and lakes. It is here where we cast our gaze today, to take a look at the varied bizarre creatures said to call these waters home. 

One very weird aquatic phenomenon can be found to the south of the main Japanese islands, in the Ryukyu Island chain, which stretches from the island of Kyushu all the way down to Taiwan, and of which the most well-known of which are the Okinawa Islands. Known for their pristine locales, beautiful scenery, and gorgeous beaches, the Ryukyu islands of Japan also have plenty of mysteries, and throughout these islands there have long been said to lurk strange creatures that have so far eluded our understanding. Here among all of the natural beauty of Japan's Southern islands seem to prowl undiscovered mysterious cryptids that we may never understand.

One of the weirdest mystery creatures said to inhabit the Ryukyu Islands is a type of alleged small, hairy, semi-aquatic ape-like creature called the Kenmun, or also known as the Kijinuma in more southern areas. The stories originate from Amami Ōshima, which is the largest island in the Amami chain of islands, in the Northern part of the Ryukyu archipelago. The Kenmun, also variously known as the Kenmon, Kunmon, Kunmu, and Nebuzawa, is said to be around 1 to 1.3 meters tall, about the size of a 5- or 6-year-old child, but with a stocky, muscular build and covered in kinky, reddish or black hair, that looks mussed, matted and dirty. The Kenmun has a face that is most often described as being like that of an ape or monkey, but also sometimes as dog-like. It is a nocturnal animal, with eyes that supposedly glow red in the dark when light catches them. The creature’s arms are disproportionately long compared to the legs, and it is said to be an agile and powerful climber.

Amami Ōshima

The Kenmun is said to be highly arboreal, making its home primarily in banyan trees, yet it is also supposedly a good swimmer, semi-aquatic, and is thought to prefer habitat near water, such as rivers, lakes or the sea. Its favorite foods are said to be fish, crab, and octopus, as well as shellfish and snails, and indeed it is thought that a sure sign of a Kenmun’s tree is the shellfish and snail shells littering the area under it. The creature is said to be particularly fond of fish eyes, which it will pop out and eat with relish. They are said to be mostly harmless, although the mostly nocturnal creatures are said to spook people at night with their eyes, which supposedly reflect light like a cat’s.

A prominent feature of the Kenmun is its powerful stench, variously described as smelling like goat, horse, and rotting yams. The smell is believed to instill great fear in animals that come into contact with it, and there have been modern accounts of this. For instance, in 1973, a rancher reported that as he moved his cows to pasture, they suddenly became spooked and refused to move. It was strange since they had never acted this way before. The curious rancher took a look around and didn’t see anything unusual, but he became aware of a thick, pungent stench in the air. It was not until the smell passed that the cows finally regained their composure. Similar effects have often been reported on horses and dogs.

Although mostly considered as harmless, the Kenmun has a somewhat bad reputation nevertheless. In folklore, it was thought to be a trickster as well as a bit headstrong, known to challenge travelers to wrestling matches. In more modern reports, the creatures are said to steal fish or bait from fishermen, and indeed Kenmun are most often seen by fisherman fishing at night. There have even been cases where Kenmun have reportedly aggressively tried to scare fishermen away from their catches. Some more violent behaviors include shrieking at passerby and hurling rocks or stones. There have even been accounts of homes being besieged by rock throwing Kenmun. One man told of seeing a small, dark form sitting alone on the beach one evening, which he at first took to be a child. When he called out to it, the figure suddenly whirled around in surprise and the man was astonished to see that it was a hairy creature like a small ape. This creature proceeded to start throwing rocks at the terrified man, even chasing him to his nearby home, where it continued to pelt the dwelling with rocks for some time before leaving the area.

Although the Kenmun has long been sighted by islanders, physical evidence has mostly taken the form of trees with a disproportionate amount of discarded shells under them, and footprints that turn up from time to time. In November 1986, a man by the name of Isamu Satoyama photographed a series of strange tracks in the sand on a secluded beach. The tracks went on for 500 meters and measured 10 cm by 30 cm in diameter. Similar trackways have been found from time to time in areas the Kenmun are said to inhabit, most often in sand but not always. There was even a plaster cast made of one such print, although it proved to be inconclusive. In more recent years, very few tracks have been found and eyewitness reports are rare.

The Kenmun is not the only type of creature like this to be found in the Ryukyu islands. It is very similar to another type of mysterious creature known as the Kijimuna, which is said to live in the more Southern Okinawa prefecture. What could the Kenmun possibly be? A new type of primate? A hominid or proto-pygmy of some sort? Are they just a figment of the imagination? The lack of any new sightings or evidence suggests that if these things ever existed at all, then they may well have already gone extinct or are close to it. If that is the case, then perhaps we will never know what they were or are.

Moving on we come to mermaids. Mermaid lore is as varied as the many cultures it originates from. As a nation surrounded by the sea, it is perhaps no surprise that Japan too has its own long tradition of mermaids. These creatures are known to the Japanese as ningyo (人魚), literally “human fish,” as well as gyojin (魚人), meaning “fish human,” and hangyo-jin, (半魚人)or “half-fish human.” Stories of fish-like humanoid beings have been reported from the waters around Japan for centuries. It is said that the first recorded account of mermaids in Japan dates all the way back to the year 619, during the reign of Empress Suiko, when one was allegedly captured in Japanese waters and brought before the court of the Empress herself. The creature was allegedly kept in a makeshift tank for the entertainment of visitors to the court.

Physical descriptions of Japanese mermaids vary; however they generally differ in appearance from the traditional image of the beautiful maiden torsos with fish tails common to Western mermaid lore. Before the influence of foreign traditions somewhat changed the image of mermaids in Japan, the Japanese Ningyo actually had little in common with their Western counterparts, both in appearance and behavior. Although they were often indeed described as having full heads of hair, the Ningyo were typically depicted as more bestial, inhuman, and somewhat grotesque looking than the more familiar European variety, with an appearance more like a cross between a fish and a monkey than that of a beautiful woman. Often the mermaids had barely human scaly arms ending in twisted claws. In many local traditions, these Japanese mermaids had no appendages at all, and were often said to be just a humanoid, ape-like, or reptilian head with sharp teeth upon a fish body instead of possessing a full human torso. The heads were sometimes depicted as being misshapen, horned, or possessing prominent fangs or rows of pointed teeth like those of a shark. Some stories tell of a more relatively normal looking human head, only attached directly to a full fish body. In other traditions, the mermaids retained a form reminiscent of the more familiar version of Western mermaids, but with a more demonic, sinister appearance or having distorted features. The more humanoid Japanese mermaids were sometimes said to have alabaster white skin and high, musical voices that sounded like a skylark or flute.

Many mystical qualities and magical abilities were attributed to the mermaids of Japan. The Ningyo were believed to cry tears of pearl, and it was thought that eternal youth and beauty would be imparted upon any human being who consumed a mermaid’s flesh. Many legends tell of women eating the flesh of a Ningyo and miraculously ceasing to age, or reverting to a younger, more beautiful form. Like many Japanese folkloric animals, merfolk were also said to have shape-shifting abilities. Mermaids taking on the form of human beings or other creatures are often mentioned in much folklore concerning the creatures. For instance, in the 1870s lighthouse keepers at the Cape Nosaapu Lighthouse in northeast Hokkaido believed that the local mermaids could turn into deadly jellyfish. These mermaids were thought to masquerade as beautiful, kimono clad women on shore that would seduce and lure men into the sea, upon which they would transform into giant jelly fish and kill anyone foolish enough to have gone for a swim with them.

For many Japanese in earlier eras, as in other parts of the world, mermaids were not mere figments of the imagination or the stories of crazed fishermen, but rather a very real feature of the ocean. Japanese fishermen accepted them as a part of everyday life and were well acquainted with them, with sightings being fairly commonplace. Throughout the 16th to 19th centuries, it was not considered particularly unusual for fishermen to tell of seeing these enigmatic beings swimming alongside their boats or attempting to steal fish from their nets.

More relatively modern accounts exist as well, such as a case in 1929, when a fisherman by the name of Sukumo Kochi captured a fish-like creature in his net that had a human face upon the head of a dog. The creature broke free of the net and escaped. During World War II, mermaids were frequently reported in Japanese waters, in particular the warm seas off Okinawa. There were even reports of Japanese navy personnel opening fire on and killing mermaids, but no bodies were ever recovered. Some reports of mermaids frolicking in the ocean were made by fairly high-ranking military officials, so it is difficult to know what to make of such reports.

Western explorers also gave accounts of seeing mermaids in Japanese waters. In 1610, a British captain allegedly saw one such mermaid from a pier at the port of Sentojonzu. The creature was cavorting in the water nearby and reportedly came quite close to the pier where the bewildered captain stood. The mermaid was described as being the head of a woman atop a body that was all fish, with a prominent dorsal fin running down the middle of the upper body. Sea traders from the west would make note of mermaids in Japanese waters on many occasions in their logbooks, and some captains even made an effort to avoid known Ningyo haunts so as not to come across the often-mischievous creatures.

Not only were Ningyo regularly sighted by various seafarers, but tales abound of them being captured by fishermen all over the country, either by accident or by those looking to gain the purported immortality bestowing meat. Throughout the 1700s and 1800s in particular, mermaids were often reportedly brought in by fishermen around Japan. The captured mermaids in some cases were said to have the ability to speak and would try to trick their captors or talk the fishermen into releasing them. Although many of these mermaids managed to break free or talk their way out of trouble, not all were so lucky.

Among the Ningyo successfully caught by fishermen, some were said to be exhibited in sideshows. In 18th and 19th century Japan, sideshow carnivals known as misemono were all the rage among the populace. These events were like festivals of sorts that featured a wide range of attractions such as acrobatics, dance, fortune telling, and arts and crafts. One very popular type of attraction was an  exhibition of strange natural phenomena and exotic animals collected from the far corners of the Earth. These were typically booths comprised of a “cabinet of curiosities” type exhibitions showcasing bizarre animals, plants, and other exotic wonders of nature from all over the world. These booths can be seen as being in many ways similar to the circus sideshows of the U.S. and Europe, attracting curious onlookers with their displays of the mysterious, strange, and sometimes downright freakish. The misemono were known for drawing huge crowds of people who would gawk at the bizarre menageries, ad there were often mermaids displayed here. It is a shame that Japan became well-known for its manufacture of fake mermaid specimens during this era, so it is unknown how real any of this was. 

Japan has its share of lake monsters as well. Perhaps the most well-known example of this comes from the majestic and iconic Mt. Fuji, one of the country's most famous and instantly recognizable landmarks. Rising up from Yamanashi prefecture, Mt. Fuji is the highest mountain in Japan, it’s majestic peak widely visible for miles around, even from the bustling metropolis of Tokyo. The mountain, which is in fact a volcano, has been revered by the Japanese people for centuries. In addition to its stark beauty, Mt. Fuji is also known for its mysteries. Sprawled out in an arc under the northern shadow of the looming Mt. Fuji are The Fuji Five Lakes, also known in Japanese as the Fujigoko, (literally, “Fujis’s five lakes”). The lakes were formed by previous eruptions of Mt. Fuji, when volcanic lava flows blocked and dammed up rivers and streams to create the lakes. These five lakes are Lake Kawaguchi, Lake Motosu, Lake Saiko, Lake Shoji (the smallest of the five), and Lake Yamanaka, which is the largest of the five and also the third highest lake in Japan. The Fujigoko are a popular travel destination for people all over Japan and are also allegedly home to a bizarre, water dwelling beast.

For years, these picturesque lakes have been the setting for a series of strange sightings of an unidentified creature in the water, which has been affectionately referred to as Mossie, or "モッシー” in Japanese, in an attempt to emulate the naming of its more famous Scottish cousin Nessie. Mossie is reported as being up to 30 metres in length, with a horny, bumpy back like an alligator or crocodile. Some reports have also mentioned a long dorsal fin like that of a shark, yet the majority of sightings have been simply of large, dark shapes swimming under the surface of the water, with no details visible. A good majority of the sightings have occurred at or near dusk, when the creature appears to be more active. Mt. Fuji's lake monster first became widely known in the 1970s, when there was a rash of sightings of something large and unexplainable lurking in the depths of the lakes. The idea of a water monster roaming the waters at the foot of the famous Mt. Fuji captured the public imagination and drew a lot of media attention at the time. People began to arrive in droves in order to not only bask in the beauty of the mountain and surroundings, but also in the hopes of catching a glimpse of the monster.

At the height of this lake monster fervor, boats descended upon the lake trying to find it, and one group of fishermen decided to try their hand at catching whatever the thing was. The fishermen spent days laying an elaborate system of sturdy nets on the hopes of ensnaring the creature, then laid in wait. Not long after, the nets were pulled up and were found to be completely shredded and ripped apart, much to the fishermen's surprise. It was surmised that only something very large and strong could have done that much damage to the nets that were used. Meanwhile, some of the boats scouring the lake came up with bizarre sonar readings of large moving shapes near the bottom. One boat captain claimed to have repeatedly picked up the sonar signature of an inexplicable dark form that he described as being around 25 meters in length. Other boats reported getting sonar hits on multiple unidentifiable shapes at the same time, which they described as almost a school of huge, eerie creatures that they insisted could not have possibly been schools of fish or geographical features.

One man, a Mr. Ken Yanoguchi, claimed to have had a very close encounter with the beast in the 1970s. While fishing on lake Saiko in his small boat, Yanoguchi reportedly bumped up against something in the water. Thinking it was a log, he went to investigate only to find a large creature of some sort lurking just under the surface with part of its back protruding from the water. The exposed part of the creature was described as black, slick, and rubbery looking. The rest of the creature had the appearance of an enormous fish or whale, and Yanoguchi himself even said that his first impression was of a whale, although he could not fathom why a whale should be out in one of the five lakes. The creature reportedly leisurely sunk beneath the water and was not seen again.

In the 1980s, sightings continued and the creature was even allegedly caught on film in October, 1987. A Mr. Yoneyama was out with three others taking pictures of the lake and its surroundings when they saw a surge of water out on the otherwise calm lake. Within this surge, they reported seeing 3 to 5 meters of the exposed back of something they could not identify, which was described as being rough like that of a crocodile. They were able to capture the animal on film, but the results are less than impressive, showing merely a dark shape and thus proving to be inconclusive. Sightings of the animal have dropped off in recent years, but a group in the village of Kamikuishiki has been investigating the Mossie phenomena since 2005.

Mossie has been sighted in more than one of Mt. Fuji's five lakes, which could be explained by the unique geological features of the lakes, namely the fact that Lake Motosu is connected to Lake Saiko and Lake Shoji by a system of underground waterways that mysterious underwater creatures could use to travel back and forth between lakes. However, what can't be readily explained is why an enormous lake monster should be here in the first place. The very nature of the lakes makes them an odd location for a lake monster to be found since the Fuji Five Lakes are not particularly ancient. It is thought that the volcanic activity that formed the lakes is very recent in geographical terms, with the lakes forming sometime during the 9th and 10th centuries. This makes it impossible for the creature to be some type of prehistoric animal trapped in the lakes millions of years ago.

The presence of a large, unidentified monster here is also further complicated by the fact that there are no rivers or natural drainage connected to the lakes either, so there is no possibility that something has travelled there from the sea through this route. In addition, many of the fish in the lakes were stocked, and there is no species of fish known there that even approaches a size large enough to cause the reports. These facts make it difficult to determine a biological possibility of just what Mossie could be. Many theories have been put forward. Ideas run the gamut from oversized introduced fish like the enormous wels catfish or sturgeon that have somehow been released into the lake. Sturgeon have indeed been introduced in some areas of Japan, but this is not known to have happened in the Fuji five lakes. As it stands, no species of fish known to inhabit the lakes even approaches the sizes reported for Mossie.

Regardless of the head scratching nature of the Fujigoko lake monster phenomenon, sightings of Mossie continue to occasionally come to this day. Is there any chance that a large, unidentified creature is lurking somewhere in these lakes? Those who swear to have seen it say yes. Giant fish or unknown monster, perhaps one of these animals is swimming out there right now, cutting a path through the tranquil reflection of Mt. Fuji upon the water.

Another account of a strange lake cryptid comes from Lake Biwa, which is in Shiga Prefecture, and is the largest freshwater lake in Japan. In the 1980s, there were several reports of giant eels inhabiting the lake. One such sighting was made by a large group of people aboard one of the lakes many pleasure boats. Startled ferry passengers reported seeing several very large eels swimming at the surface far from shore. The eels were described as being around 3 meters (around 10 feet) long, and a silvery blue color. The eels appeared to be leisurely gliding along beside the boat and were observed for around 15 minutes before moving off out of sight.

A fisherman on the same lake reported actually hooking and reeling in an eel that was reported to be around 8 feet in length. In this case, the eel was kept and eaten. Another fisherman on the lake reported seeing a similarly sized eel rooting through mud in shallow water near the shore.

Some mystery beasts have been long reported from even smaller bodies of water in Japan. Takanami Pond, in Niigata prefecture, Japan, lies 540 meters (1,722 feet) above sea level in a wilderness area. It is known for its pristine wilderness, camping, and hiking trails. It is also allegedly home to an enormous fish locals affectionately refer to as the Namitaro. The fish is said to be between 2 to 4 meters (6.5 to 13 feet) in length and covered in large scales. The Namitarou rarely comes to the surface but is known to startle people strolling along the pond from time to time. Fishermen have also claimed on occasion to have caught the beast, only to have it break their lines.

Takanami Pond

One report of a closer encounter described how a man had entered waist high water in the pond to retrieve something he had dropped. As he blindly felt through the murky water and silt at the bottom, his hand came up against what he took at first to be a large log at the bottom. It was only when this “log” suddenly began to swim away that he realized it was some incredibly large fish. The mysterious fish was so large and powerful that the sweep of its tail as it swam off actually bumped into the man and knocked him down. The man described being terrified, and quickly exited the water to see a large wake as whatever it was sank into the depths.

The pond is an odd place for such a large cryptid, as it is small and shallow, being only 13 meters at its deepest point. In addition, the area is quite popular for its hiking and camping, and there are many campgrounds, parks, shops, and restaurants in the vicinity of the pond. Nevertheless, the Namitaro has become somewhat of a legend in the area, and most people who pass through pause at the pond hoping to catch a glimpse of the elusive creature or the large wakes and waves it is said to produce as it cruises under the surface. These waves are so well-known that indeed the name Namitaro is a combination of the Japanese words for “wave,” nami, and Taro, a common Japanese first name, sort of like “John” for Westerners.

It has been speculated that the Namitaro could be a specimen of a large species of Asian carp, such as the grass carp or black carp, that has somehow been released into the pond and grown to epic proportions. These species of carp get to very large sizes that are comparable to what people have seen in the pond. The black carp, for instance, can reach up to 6 feet in length and weigh over 200 pounds. An even larger species, the Siamese giant carp, can get up to around 10 feet long. If you are ever in the area, keep your eyes open and perhaps you will see the Namitaro for yourself. Or you may want to drop a line in. You never know what you might catch.

In Yamagata Prefecture on Honshu island, Japan, there is also a small, isolated body of water by the name of Otori-ike 大鳥池, (literally translated as Otoro Pond), which lies high in the mountains, 1,000 meters above sea level. Despite its Japanese name (“ike” means “pond”), the limnology of Otori-ike is not that of a pond. It is in fact a lake, created when a landslide blocked off a mountain stream long ago. The lake is 3.2 kilometers (2 miles) around and 68 meters (223 feet) deep at its deepest point. Located within Yamagata’s largest virgin forest, Otori-ike is known for the area’s stunning natural beauty and is a haven for hikers. The lake is also known to be the haunt of a mysterious giant fish, known locally as the Takitaro.

The Takitaro are said to be enormous fish capable of reaching sizes of up to 3 meters (10 feet) long. Locals have long told of seeing these giant fish in Otori-ike, and the creatures are well integrated into the folklore of the area. Takitaro were once claimed to have the ability to bring in storms, and the sight of one was said to mean that a storm was imminent. The fish were often said to attack small boats and were blamed for the occasional disappearance of fishermen.

One old story tells of a boat that was pulled under the waves by a Takitaro as horrified villagers looked on. Takitaro were also believed to snatch deer and other animals from the lakeshore. There is one account that describes a Takitaro carcass washed up on shore that when cut open revealed the remains of a deer. Residents of the area have claimed to even catch Takitaro on occasion and in fact the fish are widely believed to be good eating.

A modern report of such a catch occurred in 1917, when workers investigating a floodgate managed to capture a fish that measured 150 cm (5 feet) long and weighed 40 kg (88lbs.). The men reportedly ate the fish, and described its meat as being quite good. Other specimens have reportedly been captured throughout the 20th century as well. Several of these captured specimens have been described as being anywhere from 160 cm (5.3 feet) to 2 meters (6.5 feet) long. Stories abound of fishermen encountering these monstrous fish right up to the modern day, with accounts of mysteriously mangled nets and fishing poles violently yanked or broken by something very large and strong. One report spoke of something that looked like a “moving log” that was witnessed to bowl right through a fishing net. According to the eyewitness, the fish was almost 2 meters long and had what appeared to be a thick layer of fat.

Other reports are somewhat more frightening. One eyewitness reported seeing a huge dark shape under the surface methodically swim about sucking ducks under the surface. The mystery monster would devour one duck, then cruise around and do it again over and over. All told, the creature was reported to have devoured at least five ducks before sinking into the depths. Another account describes a rowboat being violently rammed by something huge in the water. The terrified eyewitnesses claimed that the boat was close to capsizing when whatever it was left them alone and disappeared.

While locals have been aware of these mysterious fish for a long time, perhaps the sighting that single handedly brought the Takitaro into the limelight and to mainstream consciousness in Japan was made by four mountain climbers in 1982. Tomoya Sawa, Kenzo Matsuda, I. Onodera, and Masakazu Sato, were hiking along Otori-ike’s nearby Nao Ridge when they saw several huge fish estimated as being 2 meters (6.5 feet) to 3 meters (10 feet) long swimming through the lake’s crystal-clear water.

This sighting was a sensation all over Japan and was plastered over most major newspapers. The tale of giant fish dwelling in this picturesque mountain lake fired up the public imagination. Only adding to this fervor was footage captured by a group of TV reporters investigating Otori-ike in October 1983 in the wake of this sighting. The reporters’ footage shows three huge shapes swimming under the surface of the water. In response to the incredible amount of attention this sighting and the subsequent footage generated, a scientific expedition was mounted to the lake in 1985 in the hopes of obtaining evidence of the Takitaro. Scientists conducted a thorough search of the lake using sonar equipment, during which they made some peculiar finds. In the deeper parts of the lake, sonar picked up readings at a depth of 30 to 40 meters (98.5 to 131 feet) of what appeared to be fish much larger than any known to inhabit the area. Although the exact type of fish could not be determined, these curious sonar images seemed to confirm that something very large and mysterious was indeed lurking in the depths.

Gill nets laid out by the team also brought up some unusual findings. The nets captured several Dolly Varden trout (Salvelinus malma malma), which were much larger than usual for the species, although not nearly as large as the alleged Takitaro. In addition, Dolly Varden are represented in Japan by a landlocked subspecies that only inhabit the northern island of Hokkaido. They were not previously known to be in Otori-ike at all. Whether or not these super sized Dolly Varden were connected in any way to the giant Takitaro, they nevertheless represent an unusual finding. Another theory is that perhaps the fish are a relic population of an ancient, extinct species, or even an unknown fish species that was trapped when the landslide formed Otori-ike from a stream long ago. Whatever there creature could be, it is perplexing that it should be here, and as long as sightings continue it will keep stirring up wonder and debate.

Wonder and debate seem to be married to all of the phenomena we have looked at here, and it all paints a picture of the waters of Japan being haunts for denizens of the wild lurking beyond what we know. Are there rational answers for any of this, or are there things prowling out past the fringes of what we think we know? Who knows, but it is all a perplexing look into some lesser-known mystery beasts of the Land of the rising Sun. 

Brent Swancer

Brent Swancer is an author and crypto expert living in Japan. Biology, nature, and cryptozoology still remain Brent Swancer’s first intellectual loves. He's written articles for MU and Daily Grail and has been a guest on Coast to Coast AM and Binnal of America.

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