Oni is one of representative monsters of Japan. This monster is described by god, guardian, and just ferocious monster and ghost. First, Oni eats living beings, human, and alcohol. Second, it lives in the nature such as mountain, cave, fortresses, and islands. Third, according to the research, Oni was occurred from primitive beliefs for the plenty. Thus, in the ancient of Japan, Oni was described by god of wind, thunder, and blacksmith and guardian. Also, the body structure of Oni was more like human, and people called Onu, which means invisible and transcendental existence like a god. Actually, a name, Oni, was made from Yaksas of Buddhism, who is a demon of hell, and Onu. It shows that Oni was influenced from the cultures of other nations.