Every child in Japan knows to be careful near rivers and ponds, because of the kappa (河童, “river child”). The kappa is a small, greenish, child-sized creature that lives in water. It has a beak like a turtle, a shell on its back, webbed hands and feet, and — most famously — a dish-shaped hollow on the top of its head filled with water. As long as the dish is full, the kappa is immensely strong. If the water spills, it becomes weak, or even dies.
The kappa is one of the most widely known yōkai in Japan, and one of the most ambiguous. It drowns people and animals, pulls them into the water, and steals a mysterious organ from their bodies. But it is also polite, loves cucumbers, is fond of sumo wrestling, teaches medicine to humans, and always keeps its promises. Today it is as likely to be a cute mascot as a monster.
Appearance
Kappa descriptions vary across Japan, and the creature goes by dozens of regional names: kawatarō, gataro, kawako, suiko, enkō, and many others. The classic image, established by illustrated encyclopedias of the Edo period (1603–1868), has these features:
- The size of a child of about ten.
- Green, yellow, or blue skin, sometimes scaly or slimy.
- A face like a monkey or a frog, with a beak.
- A shell like a turtle on its back.
- Webbed hands and feet.
- A ring of hair around a dish (sara) on top of its head, which must be kept wet.
- Arms that can slide through its body, so that pulling one makes it longer and the other shorter — or that can be pulled off entirely.
- A foul, fishy smell.
In western Japan, especially Kyushu, kappa were often imagined more like monkeys or otters; in eastern Japan, more like turtles.
The Dangerous Kappa
In traditional folklore, the kappa is a real danger. It lurks in rivers, ponds, and lakes, waiting to pull people and animals into the water and drown them. It especially targets children who swim alone, and horses and cows that come to drink.
Most gruesomely, the kappa is said to pull out a victim’s shirikodama (尻子玉), a mythical ball or organ located inside the anus, which it eats or presents to the dragon king of the waters. The belief may have arisen from the appearance of drowned bodies, in which the anal sphincter relaxes.
The kappa was, in part, a way of warning children to stay away from dangerous water. Signs warning of kappa can still be seen near rivers in some parts of Japan.
Defeating a Kappa
Fortunately, the kappa has weaknesses:
- The bow. The kappa is extremely polite. If you meet one, you should bow deeply. The kappa, bound by courtesy, will bow back — and the water will spill from the dish on its head. Weakened, it must either let you go or beg you to refill its dish. If you refill it, the kappa will be bound to serve you forever.
- Cucumbers. The kappa loves cucumbers more than any other food — more even than human flesh. Throwing a cucumber inscribed with the names of your family into the river before swimming was believed to protect you. The cucumber roll in sushi is called kappa-maki in honour of this preference.
- Iron and sesame. Kappa are said to dislike iron, sesame, and ginger.
- Sumo. Kappa love to challenge people to sumo wrestling. They are very strong, but if you bow first, they will spill their water and lose.
The Kappa’s Arm and the Gift of Medicine
A common story tells of a kappa that tried to pull a horse into the river. The horse bolted and dragged the kappa back to the stable, where the farmer caught it — or a samurai cut off its arm. The kappa begged for its arm to be returned. In exchange, it promised never to harm anyone in the village again, and taught the man a secret method of setting bones or making a healing ointment.
Several families in Japan traditionally claimed that their medical recipes came from a kappa. Some temples even display what they claim to be a mummified kappa hand, such as the one at Sogenji temple in Tokyo’s Kappabashi district.
Kappa are said to always keep their word. A written promise from a kappa was absolutely binding.
Kappa and the Water God
Scholars believe that the kappa may have originated as a degraded form of a water deity (suijin). In some regions, kappa were worshipped at shrines, and offerings were made to them to ensure a good harvest and protection from drowning. The kappa’s seasonal movements — living in the rivers in summer and moving to the mountains in winter, where it became a mountain spirit — may reflect older beliefs about a god who moved between the water and the mountains with the agricultural cycle.
Some researchers have also connected the kappa with the Chinese water monkey legends, or with the Japanese giant salamander, a large amphibian that lives in mountain streams and was sometimes caught by children.
The Kappa in Literature
The novelist Akutagawa Ryūnosuke wrote a famous satirical novel, Kappa (1927), in which a psychiatric patient describes his visit to the land of the kappa. Their society, with its absurd customs — kappa babies are asked, before birth, whether they wish to be born — is a mirror of human society. Akutagawa committed suicide a few months after the book’s publication, and the anniversary of his death is known as Kappa-ki, “Kappa Day.”
The Cute Kappa
In the twentieth century, the kappa became cute. The artist Shimizu Kon drew popular comic kappa for advertising in the 1950s, and the sake brewer Kizakura has used kappa characters in its advertisements for decades. Kappa appear as mascots, in children’s television, and in many anime and manga, such as the film Summer Days with Coo (2007), about a boy who befriends a young kappa.
The Kappabashi district of Tokyo, famous for its restaurant supply stores, has a large golden kappa statue, and various towns across Japan use the kappa as a mascot.
The Kappa Today
The kappa is a perfect example of how Japanese folklore can combine the terrifying and the comic. The same creature that pulls children to their deaths also loves cucumbers, bows politely, and keeps its promises. It is a warning, a trickster, a teacher, and a friend.
Last reviewed: September 2026.