mythicallore:

     Kappa are Japanese flesh-eating water imps who live in rivers, lakes, ponds, and other watery realms. They smell like fish and are generally portrayed with the body of a tortoise, ape-like head, scaly limbs, long hair circling the skull, webbed feet and hands, and yellow-green skin. They are often depicted with a tortoise shell attached to their backs. Some say they can change color like a chameleon. They hate metal objects and loud noises.

The defining characteristic of the Kappa is the hollow cavity atop its head. This saucer-like depression holds a strength-giving fluid. Should you chance upon the quarrelsome Kappa, please remember to bow deeply. If the courteous Kappa bows in return, it will spill its strength-giving water, making it feeble, and forcing it to return to its water kingdom.

About the size of a child aged 6 to 10, the Kappa is nonetheless incredibly strong. It attacks horses, cattle, and humans, usually dragging its prey into the water, where, according to various legends, it feeds on their blood, or drains their life force, or pulls out their livers through their anuses, or sucks out their entrails, leaving nothing behind except a hollow gourd. In some tales, the Kappa is associated with theft and raping women. Stories tell of Kappa pulling little children into water and drowning them. In many localities, drowning is still referred to as Gappadoko.

Kappa are mostly evil, but not always. When benevolent, the Kappa is supposedly a skilled teacher in the art of bone setting and other medical skills. The Kappa is always portrayed as trustworthy despite its many evil ways. When captured and forced to promise never again to harm anyone, the Kappa always keeps its promise. Kappa often help or mentor those who outwit them or capture them.

Kappa are usually seen as mischievous troublemakers or trickster figures. Their pranks ranger from the relatively innocent, such as looking up women’s kimonos, to the malevolent, such as drowning people and animals, kidnapping children, and raping women.

As water monsters, Kappa have been blamed for drownings, and are often said to try to lure people into water and pull them in with their great skill at wrestling. They are sometimes said to take their victims for the purpose of drinking their blood, eating their livers. Even today, signs warning about Kappa appear by bodies of water in some Japanese towns and villages.

Kappa are also said to victimize animals, especially horses and cows. If a Kappa is caught in the act, it can be made to apologize, sometimes in writing. This usually takes place in the stable where the Kappa attempted to attack the horse, which is considered the place where the Kappa is most vulnerable.