Kappa are mythical goblins who live in holes in river banks and tend to spring out and play magical pranks on passers by. They have the body of a tortoise, the legs of a frog and, usually, the head of a monkey. They have an unpleasant tendancy to attack and devour human beings - but there is a remedy, to prevent this. The kappa is a very polite beast. It has a depression in the top of its skull which it must keep full of water, or it loses its magical power until it can get back into the water. On meeting a kappa, the best course is to bow deeply, upon which the kappa, a polite creature bows back, thus spilling its fluid and with it its magical power.