A kappa, from Japanese mythology. Skilled in bonesetting, these underwater creatures sucked the blood from their victims' anuses. They are closely associated with cucumbers(hence their skin color and texture). From my sketchbook.
The kawataro is a variety of kappa (water imp) which, according to the accompanying text, likes to eat people and practice sumo. An indentation on top of the creature's head is filled with water. The kawataro becomes weak when the water spills out.