That’s a pretty neat idea, anon, though I don’t think she’d have to wait until ANBU to get that title (and having a title as an ANBU that isn’t your animal codename might be a bit counterproductive anyway?)
Because if you consider it? Sakako (maybe) doesn’t have the hawk contract, but she does have an emergency summon and combining that with the idea that she can manifest people’s angry ghosts AND that Tengu (according to wikipedia, at least) “possess people, especially women and girls, and speak through them,” to a very superstitious person and in the right series of events she would look like a Tengu.
Especially if it’s… let’s see… a business mogul or corrupt noble who is going to deforest/mine a place that’s sacred to the local village. And the local village hired Next Gen Team Seven for a really small task (maybe help clean the shrine up on the mountain, or escort the village chief who is old up the mountain so he can clean the shrine, etc. etc.) but then business mogul / corrupt mogul shows up and does *typically upper class awful things* and obviously any Team Seven wouldn’t let this happen so they kind of stay and fight and… well.
What Team Seven doesn’t have a flare for the dramatic?
Sakako uses a genjutsu on the bad guy, brings their ghosts to life (so to speak) and maybe has to summon her dad’s hawk when she gets pushed off a cliff and it’s all just. Bad guy has had a religious experience and learned the error of his ways and, hey, the local village can actually help business person/noble how to mine/harvest whatever they were trying to get in the first place in a sustainable way without razing everything to the ground (and that brings new blood back to the village which was, admittedly, beginning to age out–no one in that village was younger than forty, so there wasn’t much future for the village).
… so maybe it’s not so much her title as it is a significant note that would be put on her bingo book page (“actually possessed by a tengu? can summon tengu and ghosts?” Poor Rock nin are so damned confused.)