If you study classic mythology and fairy tales, you soon come to realize that a lot of the mystical beings of folklore aren’t really all good or all evil. Many of them are just out for their own interests, and help or hinder others as suits them at the time. Others have been both feared and loved in different eras. That appears to be the case with the tengu, Japanese demons who have been portrayed at various times as ferocious creatures and respected keepers of mountains. The Japanese tengu are thought to derive from the Chinese tiāngoǔ, which literally means “celestial dog.” These Chinese creatures were typically portrayed as meteor-dogs, which would eat the sun during an eclipse.
They were sometimes described in other ways, however, and the derivative tengu are essentially bird-demons. They were said to live in the wild forests and mountains, and were sometimes regarded as the spirits of priests and rulers. They were destructive, heralded war, and were known for capturing people and bringing them back insane. In fact, they apparently force some people to eat shit. Literally.
The softening of the tengu is thought to have been due to the eventual reconciliation between Shintoism and Buddhism. The Buddhists came to associate the tengu with the garuda, bird-people based on the Hindu bird-god. As such, the tengu came to be seen as merely mischievous rather than wicked, and many stories apparently involve their helping lost children find their way home. They protected the mountains and the temples there, and trained the yamabushi warrior-monks.
They could still be quite tricky and dangerous, but they came to be seen more as guardians of nature than agents of chaos.
The magical powers possessed by tengu include shape-shifting, teleportation, and telepathy. They are also skilled martial artists.
As powerful as they are, folk tales often portray them as being fairly easily tricked. March Laumer actually featured tengu in one of his Oz books, The Vegetable Man of Oz, which takes place during World War II and has the tengu transforming some people (including Jellia Jamb and Trot’s mother) in ways that reflect their flaws.
Sources I consulted in writing this:
Wikipedia entry on tengu
Japanese Buddhist Statuary – Tengu: The Slayer of Vanity
The Obakemono Project
And here’s the picture I saw on Tumblr that inspired me to write about this topic tonight:
Over time, the bird beaks of tengu came to be replaced in art by really long noses, as seen here.