Yami to Boushi to Hon no Tabibito

Japanese Title: ヤミと帽子と本の旅人

English Title: Traveller Yami, Hat and Book

Plot
The story follows the travels of Hazuki Azuma, a tall, brooding high-school girl, as she searches for her adopted older sister and love interest, Hatsumi, in many different "book worlds". After the disappearance of her sister, a talking parakeet nicknamed Ken-chan introduces Hazuki to Lilith, the caretaker of the Great Library. Each book in the library contains a different world, and the guardian of the library takes on the title Yami.