Tengu are a class of supernatural creatures found in Japanese folklore, art, theater, and literature. They are one of the best known youkai (monster-spirits) and are sometimes worshipped as Shinto kami (revered spirits or gods). Although they take their name from a dog-like Chinese demon "Tiangou", the tengu were originally thought to take the forms of birds of prey, and they are traditionally depicted with both human and avian characteristics. They appear in the children's story "Banner in the sky" when the main character trips over one and falls off the face of the mountain. The earliest tengu were pictured with beaks, but this feature has often been humanized as an unnaturally long nose, which today is practically the tengu's defining characteristic in the popular imagination.
Buddhism long held that the tengu were disruptive demons and harbingers of war. Their image gradually softened, however, into one of protective, if still dangerous, spirits of the mountains and forests. Tengu are associated with the ascetic practice known as ShugendOU, and they are usually depicted in the distinctive garb of its followers, the yamabushi.
The tengu in art appears in a large number of shapes, but it usually falls somewhere between a large, monstrous bird and a wholly anthropomorphized being, often with a red face or an unusually large or long nose. Early depictions of tengu show them as kite-like beings who can take a human-like form, often retaining avian wings, head or beak. The tengu's long nose seems to have been conceived in the 14th century, likely as a humanization of the original bird's bill. The tengu's long noses ally them with the Shinto deity Sarutahiko, who is described in the Japanese historical text, the Nihon Shoki, with a similar proboscis measuring seven hand-spans in length. In village festivals the two figures are often portrayed with identical red, phallic-nosed mask designs.
Some of the earliest representations of tengu appear in Japanese picture scrolls, such as the Tengu-zoushi Emaki (天狗草子絵巻), painted 1296, which parodies high-ranking priests by endowing them the hawk-like beaks of tengu demons. Tengu are often pictured as taking the shape of some sort of priest. Beginning in the 13th century, tengu came to be associated in particular with the yamabushi, the mountain ascetics who practice Shugendou. The association soon found its way into Japanese art, where tengu are most frequently depicted in the yamabushi's distinctive costume, which includes a small black cap (頭襟＝とうきん) and a pom-pommed sash (結袈裟＝ゆいげさ).
Tengu are commonly depicted holding magical hauchiwa (羽団扇), fans made of feathers. In folk tales, these fans sometimes have the ability to grow or shrink a person's nose, but usually they are attributed the power to stir up great winds. Various other strange accessories may be associated with tengu, such as a type of tall, one-toothed geta sandal often called tengu-geta.