Kappa (河童) Yokai (妖怪)

The kappa, also known as the kawataro, komahiki, or kawatora, is a species of yokai from Japanese folklore that lives in rivers or lakes.
They like human flesh, especially that of children, they also like to spy on naked women while they bathe in rivers.
To avoid being eaten by a kappa you can give them a cucumber, since they like it better than human meat, or bow to it, since being polite creatures they will bow to you, doing so will cause the sacred water to fall from their head, so they will lose their powers and you can easily catch it.