Even in such position, her hair does not move. Must be made of wax.

Maybe she's diving backwards and the hair is being swept in the direction of her torso by aerial drag.

diving backwards headfirst into a shallow brook full of rocks? Not the best idea...

Looks like she's in the middle of an attempt to do a backflip. Still, her hair does seem rather stiff.

What's that in her hand, a camera? Also, she seems to have wings, so diving backwards ABOVE a stony brook may not be the same as diving backwards INTO it. :P

She's using that giant leaf in her hand to hover in mid air by flapping it rapidly.

She's dressed like a tengu, but whether she actually is one...

EDIT: Looking at her name, of course she is a tengu... So much for questioning it.