Kappa (“river-child”), alternatively called Kawatarō (river-boy”), Komahiki (“horse puller”), or Kawako ( ”river-child”), are ayōkai found in Japanese folklore, and also a cryptid. Their name comes from a mixture of the word “kawa” (river) and “wappo,” an inflection of “waraba” (child). In Shintō they are considered to be one of many suijin (“water deity”), their yorishiro, or one of their temporary appearances.A hair-covered variation of a Kappa is called a Hyōsube . There are more than eighty other names associated with the kappa in different regions which include Kawappa, Gawappa, Kōgo, Mizushi, Mizuchi, Enkō, Kawaso, Suitengu, and Dangame. Along with the oni and the tengu, they are one of the most well-known yōkai in Japan.
Kappa are similar to Finnish Näkki, Scandinavian/Germanic Näck/Neck, Slavian Vodník and Scottish Kelpie in that all have been used to scare children of dangers lurking in waters.
It has been suggested that the kappa legends are based on the Japanese giant salamander or “hanzaki”, an aggressive salamander which grabs its prey with its powerful jaws.
Kappa are typically depicted as roughly humanoid in form, and about the size of a child. Their scaly, reptilian skin ranges in color from green to yellow or blue.Kappa supposedly inhabit the ponds and rivers of Japan and have various features to aid them in this environment, such as webbed hands and feet. They are sometimes said to smell like fish, and they can certainly swim like them. The expression kappa-no-kawa-nagare (“a kappa drowning in a river”) conveys the idea that even experts make mistakes. Although their appearance varies from region to region, the most consistent features are a carapace, a beak for a mouth, and a plate (sara), which is a flat hairless region on top of their head that is always wet, and which is regarded as the source of their power. This cavity must be full whenever a kappa is away from the water; if ever dries, the kappa will lose its power, and may even die, according to some legends. Another notable feature in some stories, is that the kappa’s arms are said to be connected to each other through the torso and able to slide from one side to the other. While they are primarily water creatures, they do on occasion venture on to land. When they do, the plate can be covered with a metal cap for protection. In fact, in some incarnations, kappa will spend spring and summer in the water, and the rest of the year in the mountains as a Yama-no-Kami (“mountain deity”). Although they are reported to inhabit all of Japan, they are often said to be particular to Saga Prefecture.