Tengu (Japanese: 天狗, lit. "Heavenly Dog" or "Heavenly Sentinel") are a type of legendary creature found in Japanese folk religion. They are considered a type of yōkai (supernatural beings) or Shinto kami (gods). The tengu were originally thought to take the forms of birds of prey and monkey deity, and they are traditionally depicted with human, monkey and avian characteristics. Sarutahiko Ōkami is considered to be the original model of Konoha-Tengu (a supernatural creature with a red face and long nose), which today is widely considered the tengu's defining characteristic in the popular imagination. He is the Shinto monkey deity who sheds light on heaven and earth. Some experts theorize that Sarutahiko was a sun god worshiped in Ise region prior to the popularization of Amaterasu.
Buddhism long held that the tengu were disruptive demons and harbingers of war. Their image gradually softened, however, into one of protective and even manifestations of buddhist deities, if still dangerous, spirits of the mountains and forests. Tengu are associated with the ascetic practice of Shugendō, and they are usually depicted in the garb of its followers, the yamabushi.
The tengu in art appears in a variety of shapes. 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. This feature allies them with the Sarutahiko Ōkami, who is described in the 720 CE text the Nihon Shoki with a similar nose measuring seven hand-spans in length. In village festivals, the two figures are often portrayed with identical red phallic-nosed mask designs.