Monster of the Day: The Kappa

Source:  Japanese folklore
Location:  ponds and lakes of Japan
Threat Assessment:  2.  They do have claws, and they can drown you.  Kappas though tend toward mischief than mayhem.  They are green with turtle shell backs (which provides some protection)
Limitations:  Oddly kappas have a sort of bowl on the top of their heads filled with water.  If they lose their water they lose their power, so tricking them to bow is an excellent way to gain the upper hand.  They also love cucumbers.