Many of the stories you still see today are inspired directly and indirectly from various myths. For the 2015 A-Z Challenge, I'm going to share mythology from all over the world - myths that are familiar and obscure.
Every culture has their own version of demons, and the Japanese is no exception. Oni is a general term for demons, devils, trolls, ogres, and other nasty creatures. They usually have horns, fangs, claws, and have blue or red skin. Many myths also have oni act as shapeshifters.
Japanese villages would hold a ceremony once a year to keep the oni away. They'd roast soybeans and throw them around, expelling any oni that might be hanging around. Within wealthy households, priests would purify the building and cleanse the area of any oni energy hanging around.
In more modern times, people would weak oni masks and run around while people threw soybeans at them. I don't know about you, but that sounds like a heckuva lotta fun!
Homes were NEVER built towards the northeast, as this direction was called the "demongate." Temples often faced northeast to help protect the area from demons.
Oni were often the bad guys in countless tales, and even to this day, lots of Japanese anime books and movies still use oni as their antagonists.