Oni

Oni (鬼?) are a kind of yōkai from Japanese folklore, variously translated asdemons, devils, ogres, or trolls. The word "oni" is sometimes speculated to be derived from on, the on'yomi reading of a character (隠) meaning to hide or conceal, as oni were originally invisible spirits or gods which caused disasters, disease, and other unpleasant things.

Overview
Oni are humanoid for the most part, but occasionally, they are shown with unnatural features such as odd numbers of eyes or extra fingers and toes .Their skin may be any number of colors, but red and blue are particularly common.

They are often depicted wearing tiger-skin loincloths and carrying iron clubs called kanabō (金棒?).