O is for... Oni

Source: Wikimedia Commons

Oni were pretty nasty monsters found in Japanese mythology. With large mouths, horns, pointed nails and the ability to fly, they weren't pleasant to look at either. 

Other aspects of their appearance vary depending on the story – sometimes they were said to have three eyes, or the head of a horse or ox. It was also thought that a woman suffering from intense grief or jealousy might be transformed into an Oni.

Oni were said to haunt people who didn't live good lives, and the Oni waited around to steal their souls when they died. There are also some artistic representations and legends which tell stories of Oni who acted like bogeymen, scaring young children. 

A Buddhist sage called Nichiren said that Oni caused terrible events such as earthquakes and war, and also unexplained natural phenomena such as eclipses. They were also thought to cause illness and plague. The Japanese people weren't completely helpless against the Oni, however, as an annual festival called the oni-yarabai, was held to oust them.