Ao-oni

The creature's name carries a translation problem inside it. Ao (青) does not mean «blue» in the narrow sense the English word has: in classical Japanese it covers the whole band running from blue to green, and that use is still alive in ordinary speech today, where the green traffic light is called ao, and so are new leaves and a green apple. That is why the ao-oni is painted sometimes a deep blue and sometimes a frank green, without anyone taking the two for different creatures.

That red and blue should be precisely the oni's two default colours is no accident either. Aka and ao are, along with shiro (white) and kuro (black), the four oldest colour terms in Japanese, and the only ones that work as native adjectives; every other colour name is a loanword or derived from the name of a thing. When a popular tradition needs two opposed colours, it reaches for the ones the language hands it first.

There is a tension worth stating plainly, because it shows the moment you look at pictures. The doctrinal scheme of the hindrances needs five separate colours and therefore distinguishes blue from green. Popular iconography does not need that separation and does not make it: outside the list, the green oni and the blue oni are the same one, and it is the ao-oni.

Within the way Japanese popular Buddhist tradition distributes the five hindrances among colours, the blue oni is assigned shinni (瞋恚): anger, ill will, rancour, the urge to harm another. Not cunning. Not calculation. Aversion, and nothing but aversion.

It is worth insisting, because the opposite attribution is everywhere. Red is the colour of fire, anger is imagined hot, and the reasoning closes on itself: people end up saying that the red oni is the furious one and that the blue one, by elimination, is the cold one who thinks. In the scheme actually used it is precisely the other way round. Red is the one who craves; blue is the one who hates.

From that follows something that changes the whole reading of the being. The ao-oni is no strategist, no tactician, no serene intelligence set against his companion's brute force: the tradition assigns him no cunning whatsoever. It assigns him aversion, which in Buddhism is one of the three roots of evil alongside craving and ignorance, and the only one of the three aimed at someone else. His part is not to think but to lay into his victim. The figure of a tempered, reasonable blue oni does not come from the sources: it comes from turning the scheme upside down and then filling the resulting gap with a character.

The oldest surviving description of a group of oni with their colours is in the Uji Shūi Monogatari, the tale collection compiled around 1220. In the third story of the first book, an old man hidden in the hollow of a tree watches a hundred of them arrive by night, and the text paints them thus: the red-coloured ones wore something blue, the black-coloured ones had bound something red as a loincloth, some had a single eye and some had no mouth.

It is worth pausing on what is not there. There are no two opposed figures and no pair of complementary characters: there is a motley crowd in which colour mixes and crosses, in which blue appears as clothing rather than skin, and in which none of the hundred has a name or a character of his own. That is where the matter stands in the thirteenth century.

The other place where the ao-oni genuinely belongs is the Buddhist hell. In the iconography of the Jigoku, the oni with flat-coloured skin are the gokusotsu (獄卒), the subordinate corps that carries out the sentences of King Enma: they neither judge nor are judged, they apply the torment. The only ones with names of their own within that corps are Gozu, the ox-headed, and Mezu, the horse-headed. The rest, the blue one among them, are rank and file. And that is exactly his standing in the tradition: a blue oni is not a character, he is a post that someone fills.