Monster that lives in the sewer. It swims around the sewer and crawls out to hunt for women. Its head makes a discordant noise when hit.
There are only a handful of these in the game, and they're all in fixed battles. You shouldn't have much trouble with them at all. Take these things out first when you encounter it in the Sewers, since they use a healing ability they will use on the Water Tiger when it's damaged.
The Kappa is based on the Japanese mythical water beast of the same name. It is said to behave mischeivously.