Tengu are Japanese bird spirits of the wilderness that guard the forest. They are shape-shifters, and may not show their true form, but if you do happen to see it, there are two different true forms Tengu take. One is called Karasu Tengu, or Crow Tengu, has a human body with a crow head and are covered with feathers. and their hands and feet are tipped with claws instead of digits. The other kind of Tengu is called Yamabushi Tengu, or Mountain Priest Tengu. These have human form, but have bright red faces and longer beak-like noses.
Tengu play the role of the trickster and are known to start arguments, start fires, steal children, or drop things on people from above. Think of the evil flying monkey in the Wizard of Oz and you kind of have an idea, kind of.
They aren’t always bad however. Tengu are called upon to help locate missing children. Also, if they favour you they can transfer their powers to you, which is good if you’re the warrior type. Tengu are master weapon smiths and are very skilled in both Kendo (fencing) and ninjitsu (ninjas). They are also very skilled magicians and occultists and are able to control the weather.
Tengu predate Buddhism in Japan and openly resist it in legends. They often symbolize a resistance to Buddhism. Many of their shrines are in the mountains and a common offering to give is sake, mochi, or rice cakes, but they’ll take what they can get.
Here’s a page with a little bit more information http://www.onmarkproductions.com/html/tengu.shtml And here also http://totaljapandemonium.wordpress.com/2011/03/31/yokai-report-tengu/