Aya

Aya is a Living Painting girl who, like many other people, was drawn into the world of Arbatel by the magic of the Grimoire and is currently a third year student at the Grimoire High School. While Kimihito and his household girls were trying to discover Arbatel's true identity, Aya, due to her connection to books, was one of the three Liminal girls (alongside Maika and Shii-Mii) they suspected of being Arbatel in transformation, although this suspicion was ultimately proven wrong.

Zoological Classification
Living Paintings are a type of Liminal that looks like a picture, but is able to move within it's canvas.

Trivia

 * Aya is the third Liminal girl in the series after Draco and Gill who is revealed to be a lesbian.