Kappa
This is a hybrid beast from Japanese mythology that possesses the head of a monkey, the shell of a turtle, and the legs of a frog. It inhabits ponds and streams.
Endowed with remarkable strength, it is said to have the ability to drown and devour human beings. Among its habits is also the sucking of blood, for which reason it might be considered a kind of vampire.
Despite its courteous manners, in order to defeat this beast one must force it to perform a bow in such a way that it spills a liquid contained in a cavity located on its head; this would deprive it of its incredible powers, as that very liquid is the source of its supernatural strength.