Arya is a mysterious silver-haired boy who appears in every episode of the anime and during certain times in the game. In the anime he claims to be cleaning up after Hazuki and Lilith. Also, he offers to perform repairs on Tamamonomae's Space Hall. He is the narrator of the story, and his short exits and introductions are often the only transition between stories. He is always cosplaying as some type of character or animal.
At the end of the anime series, he is shown closing a book that seems to contain the world of the Book Keepers.