Aka-oni

The oni did not start out like this. In the Nihon Ryōiki, the oldest collection of Buddhist tales in Japan (compiled around the year 822), the oni are the envoys King Enma sends to fetch the dying, and the text describes them as minor officials from an office of this world: they have human shape, they are carrying out an errand and they hold a list. There are no horns, no fangs and no coloured skin.

The image anyone recognises today was fixed later. First in the Buddhist iconography of hell, where the torturers of the damned appear with monstrous bodies and flat coloured skin; and above all in the illustrated books and prints of the Edo period, when the look of each creature was standardised in catalogues that copied one another. That is where the horns come from, and the wild mane, the tiger-skin loincloth and the spiked iron club.

The aka-oni is the end point of that drift and, at the same time, its default form: when someone draws "an oni" with no further specification, this is what they draw. Which is why the first thing to say is that its appearance is not eternal but the arrival point of a thousand years of drawing.

The colour of an oni is not decoration or a temperament: in Japanese popular Buddhist tradition it points to the five gai (五蓋), the five hindrances that obstruct practice and that the canon lists as desire, ill will, torpor, restlessness and doubt. A colour was assigned to each hindrance, and that is where the red, blue, yellow, green and black oni come from.

The red oni gets ton'yoku (貪欲), craving: the desire that grips and does not let go. It does not get anger. Anger, shinni, belongs to the blue oni, and this is worth saying because the opposite attribution is so widespread that it passes for common knowledge: red is the colour of fire, one thinks of rage, and the reasoning closes there. In the scheme actually used, red is the one that wants, not the one that erupts.

It is also worth dating the correspondence rather than assuming it is simply ancient. The list of the five hindrances is canonical Buddhist doctrine and long predates Japan; assigning a colour to each one is a later Japanese development, spread above all with the practice of Setsubun as it is celebrated today. In other words: the list is old, the palette is recent. Both things are true and they do not mean the same.

The aka-oni is driven out once a year. At the festival of Setsubun, the eve of the beginning of spring, roasted soybeans are thrown through the house with the cry "oni wa soto, fuku wa uchi": out with the oni, in with fortune. It is the most widespread Japanese domestic rite involving a supernatural being, and it works the opposite way to an exorcism: it does not destroy him, it puts him out, and he will be back next year.

In the tales his home is Onigashima, "the island of the oni", where the hero of Momotarō goes to recover what was plundered. And his weapon is the kanabō, an iron club bristling with studs, so bound up with him that it produced a proverb still in use: oni ni kanabō, "a kanabō for the oni", said of anything that reinforces someone already more than formidable.

One final warning, because it is the commonest error with this figure. The idea of a red oni and a blue one forming a fixed pair, with complementary characters and a friendship between them, is a twentieth-century literary development and not a traditional motif. In earlier folklore the colours do not pair off two individuals: they distribute a doctrine among several interchangeable figures. No old tale presents these two as a duo.