Hiyori Iki
A fictional character from the anime and manga "Noragami". She's about 15 at the beginning and saves Yato, a minor god of calamity, from getting hit by a bus. This causes her to be a half ayakashi. Now she has a habit of slipping out of her body into that half ayakashi form with a pink "tail" (the chord that connects her half ayakashi form with her human body). She's saved Yato and Yukine (Yato's shinki) multiple times which shows she's brave and can be useful.
That girl saved me from getting hit by a bus. Her name must be Hiyori Iki.