HP x Nuramago
Fem!Harry x Zen (Or another bird yokai)
Pheonix!Harry
Fawkes is Harry's "Father"
During the chamber incident, when Fawkes saved Harry he had to give her more tears than is normally advised. This and the great quantity of basilisk venom now running through her veins awakened her blood. She became at this time a quarter yokai.
She had no real clue or any idea about it. (Fawkes kept an even closer eye on her now though, and would visit her more often too since he could feel a bond between them).
A few years later during the last battle, when she dies, she meets Fawkes (who had gone missing after Dumbledore's death [But had in actuality gone to visit some old allies in Japan, looking for sanctuary for his child]), in Limbo. And it was there he spoke to her and explained all the unexplainable things to her (like how she healed so much faster than normal, how when she used fire magic it was so powerful, and how her voice at times could 'reflect/affect' moods), he explained that he had given her a lot of his essence, which basically meant he in a way adopted her and made her kin. And now he wishes to give her more so that she can survive her last ordeal and finally be free, so that she can start anew. Harry asks for clarification, and finally agrees, and in a burst of flames Fawkes flies through her leaving behind the bulk of his power/essence/fear. This turns her into 3/4 yokai (her parents magical blood and them being humans makes up the last fourth). Fawkes then reappears in front of her greatly weakened and beginning to fade, Harry panics and begs him not to leave her too, but Fawkes is tired and has been around for a very long time, and wishes to rest. As his last gift to his child he bestows upon her his knowledge for her to gain and unlock in the future as she needs it.
Fawkes then fades completely, and Harry boards the train to return her to the living plain. Where she then precedes to defeat Voldemort and end the war. Soon after she starts to steadily withdraw from the Wizarding world and all she met through it. Harry makes plans through the goblins to finish all required education (both magical and mundane, and to learn Japanese), to acquire safe traveling means to Japan, and to shift all of her monetary value to the country of the Rising Sun. She then buys all that she might possibly need for her new life.
Once all of this is finished she just seems to vanish to the Wizarding populace and no matter what they do to find her they are unsuccessful. (Mainly cause they tried finding her by using her name [which she has changed], and her blood [which changed (or kept changing) with her transformation], so they had no means to find her).
So Harry (new name needed, most likely a flower or flame related one), heads to Japan where she makes the journey to the Nura Clan house. It takes her a few days/weeks because other yokai (and 'exorcist'/Omnyouji) can sense what she is and her species, which has basically died out, is highly coveted for their healing abilities. So she has to escape from all her pursuers (some who wish her only harm). When at last she has reached Nura territory, she is accosted once more and this time she can't escape. Luckily for her someone from the clan hear her calling her help, and come to help her (she wasn't too far from either First Street, or the main house), and right when they are about to reach her she bursts into flames in a panic and incinerates her attacker. Her would be rescuer (a Human Rikuo perhaps? Remember this is just before the series begins), tries to calm her down and wit their calm patient voice succeeds. They ask her name and how they can help her, and Harry explains that her father told her to come and to seek the Nura clan for sanctuary and protection, and that she would have been there by now had both yokai and humans not tried to capture her continuously. When her 'rescuer' explains they are from the Nura clan and that she was basically right outside the gates, they show her in and lead her to the Supreme Commander (Harry is extremely relieved).