Oni vs. hannya

Every year on Setsubun (around 3 February), the day before the old calendar's start of spring, households across Japan throw roasted soybeans at the door, out the window, and often at a family member wearing an oni mask. Everyone shouts “Oni wa soto! Fuku wa uchi!”

The custom grew out of tsuina, demon-expelling rites held at the imperial court in the Heian period (794–1185). A thousand-odd years later, the oni is still the one getting pelted.

Here's the twist. The same face people chase out at Setsubun also gets hired as a guard. Look up at an old Japanese roof and you may find onigawara, ridge-end tiles carved with an oni's face, which were traditionally believed to keep evil away from the house below.

Scare off the demon. Then put a demon on the roof to scare off everything else.

Masks work the same way. In Noh, putting on the mask is how the actor becomes something else for a while. You don't wear an oni to look evil. You wear it to be the thing other things are wary of.

The kanabō (金棒) is the studded iron club an oni is usually drawn carrying. The saying oni ni kanabō, “an oni with an iron club,” describes something already strong being made unbeatable. Think of it as the Japanese version of an unfair advantage.

An oni mask shows a demon-ogre from Japanese folklore. It's traditionally tied to both danger and protection: the face that gets driven out at Setsubun, and the face on the roof keeping other evils away. Wearing one doesn't make you anything. Knowing which one you're wearing is the point.