Ятаґарасу

The unnamed magus who trained Haruri Borzak is an elderly magus who possesses the form of a young girl with a crow familiar. It is unknown if she really is over eighty years old or if she inherited her Magic Circuits complete with the knowledge of their previous owners. Her crow may also have the capacity to speak and may be a part of herself. She is a magus who, despite belonging to the Clock Tower, keeps her distance from it out of dislike for its power struggles. After the death of Haruri's parents, she took her in as her ward, but not her apprentice, and became her legal guardian.

Years before Fate/strange Fake, when Haruri was 14, she tried to dissuade her charge from joining the True and False Holy Grail Wars and collaborating with the monster Francesca Prelati all for the sake of her vendetta against the Mage's Association and the World of Magecraft, to no avail. And since Haruri was not her apprentice, she could not force her to do anything.