Tengu, translated as "heavenly dogs", are a class of supernatural creatures found in Japanese folklore, art, theater, and literature. They are one of the best known "yokai" (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 childrens 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 Shugendo, 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 and an unusually large or long nose. Early depictions of tengu show them as a bird-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 sometime 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 Tenguzoshi Emaki, painted ca. 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 Shugendo. 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 and a pom-pommed sash. Tengu are commonly depicted holding magical hauchiwa, 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.
The term tengu and the characters used to write it are borrowed from the name of a fierce demon from Chinese folklore called tiangou. Chinese literature assigns this creature a variety of descriptions, but most often it is a fierce and anthropophagous canine monster that resembles a shooting star or comet. It makes a noise like thunder and brings war wherever it falls. One account from the Shu Yì Jì ("A Collection of Bizarre Stories"), written in 1791, describes a dog-like tiangou with a sharp beak and an upright posture, but usually tiangou bear little resemblance to their Japanese counterparts.
The 23rd chapter of the Nihon Shoki, written in 720, is generally held to contain the first recorded mention of tengu in Japan. In this account a large shooting star appears and is identified by a Buddhist priest as a "heavenly dog", and much like the tiangou of China, the star precedes a military uprising. Although the Chinese characters for tengu are used in the text, accompanying phonetic furigana characters give the reading as amatsukitsune (heavenly fox). M.W. de Visser speculated that the early Japanese tengu may represent a conglomeration of two Chinese spirits: the tiangou and the fox spirits called "huli jing".
How the tengu was transformed from a dog-meteor into a bird-man is not clear. Some Japanese scholars have supported the theory that the tengu's image derives from that of the Hindu eagle deity Garuda, who was pluralized in Buddhist scripture as one of the major races of non-human beings. Like the tengu, the garuda are often portrayed in a human-like form with wings and a bird's beak. The name tengu seems to be written in place of that of the garuda in a Japanese sutra called the Enmyo Jizo Kyo, but this was likely written in the Edo period, long after the tengu's image was established. At least one early story in the Konjaku Monogatari describes a tengu carrying off a dragon, which is reminiscent of the garuda's feud with the naga serpents. In other respects, however, the tengu's original behavior differs markedly from that of the garuda, which is generally friendly towards Buddhism. De Visser has speculated that the tengu may be descended from an ancient Shinto bird-demon which was syncretized with both the garuda and the tiangou when Buddhism arrived in Japan. However, he found little evidence to support this idea.
A later version of the Kujiki, an ancient Japanese historical text, writes the name of Amanozako, a monstrous female deity born from the god Susanoo's spat-out ferocity, with characters meaning tengu deity. The book describes Amanozako as a raging creature capable of flight, with the body of a human, the head of a beast, a long nose, long ears, and long teeth that can chew through swords. An 18th century book called the Tengu Meigiko suggests that this goddess may be the true predecessor of the tengu, but the date and authenticity of the Kujiki, and of that edition in particular, remain disputed.