Despite being tritagonist, this was merely a misinformation campaign both to hide her true nature and true Tritagonist.
She has long, wavy brown hair and black eyes. She wears a yellow trench coat, white button-up blouse, pale pink bow-tie, white pants, a brown belt and gray-black boots. On the back of her belt is a pouch in which she keeps her trusty camera. She also wears a brown watch on her left wrist, hidden under her sleeve.
Emmy Altava is a strong-willed young woman who loves taking pictures, and takes them whenever and wherever she can. She has a feisty side to her, but is usually very kind, caring and protective. She loves to tease with Luke about who's the number one assistant to the professor, and the two have a brother/sister type relationship. She is also a very nimble fighter, as seen in Last Specter and Eternal Diva.
Not much is known about her early life. In Last Specter, it is revealed that Professor Layton saved her from being arrested six years prior. She had been accused of stealing a boy's wallet by Inspector Grosky, but the passing-by professor deduced that the boy had planted the wallet in her bag to avoid trouble with his mother. As Layton left, Emmy followed, trying to find out who her savior was. Inspector Grosky told her that he is Hershel Layton, and Emmy noted that she would have to remember that.