User blog comment:Hitsuji Mamoru/Servant Creation Room 2 : Guess of the Who/@comment-32599925-20170908002630/@comment-32599925-20170910013012

Nope. There was no mention of her being an avatar or any similar manifestation in the original material. She's her own being.

Hint: Her Noble Phantasm has been toned down significantly from the act which inspired it.