I read she got introduced in Fate/Extra CCC but seems like no pics wound up in Danbooru until she got a major role in Fate/Samurai Remnant.
What a great game by the way, my son was watching me play and was quite surprised that it wasn't full of hypersexualized characters. Aria is an example, I was looking for my favorite E Cup Kitsune to return but got this instead. Unlike Medb who is a rider because she wants to ride your p3s, Aria wants to put her arms around your neck and ride on your back.