Yuuki was never the type of girl that talks a lot, actually, not even the type to ever become a ninja in the first place, by coming from a family as common as hers.
There is no information about any ninjas in her family bloodline, nor even in her wildest dreams, would she think of becoming a ninja herself... Until one day.... A day that, in teory, did not even happen for most of her family, where her younger sister, somehow, desappeared.
Nobody was able to find her. Nobody saw her. Nobody cared to look close enough. Until the moment where a ninja, a very special one, an AMBU, jumped out of the roof, caring not other than her sister, safely there, right before her young eyes.
Yuuki could not forget that moment, that vision, those calculated movements, that mask...
In the same moment, she decided to become a ninja, but not a simple one, and yes, an AMBU.
That shy, clumsy, and kinda slow girl, that owned her bright/strong pink hair from her grandmother, decided to aply for the ninja academy, and was the first in line to pass the academy exams.
Of course, not even a single person in the family cared about that, nobody believed she would make it. But she did.
She'll discover that, not only what she's capable of, but what it takes, to become a true ninja.