The Director of the Library. A woman with light blue short hair who acts like a somewhat sheltered young lady. She uses the Library's power to send invitations to guests. She is searching for the "One Absolute Book" that contains everything. She considers Roland her closest friend.

The Patron Librarian of the Floor of General Works. A black-haired man with a sociable personality who somehow wandered into the Library despite it being inaccessible without an invitation, leading Angela to hire him. He is quite cynical.

The Patron Librarian of the Floor of History. A woman with long chestnut hair who is optimistic but a bit of a klutz. A hard worker who often scolds Netzach for slacking off. She tends to be hostile toward Angela and Roland.

The Patron Librarian of the Floor of Technological Sciences. A man with short purple hair that covers one eye. He is strict about discipline and grooming, frequently pointing out that Roland's tie is crooked. He tends to be hostile toward Angela and Roland.

The Patron Librarian of the Floor of Literature. A woman with a brown bob and a prominent cowlick. She faces the layered aspects of human good and evil, much like literature. She has a kind personality and holds a grudge against Angela but never shows it. Her cowlick reacts to her emotions.

The Patron Librarian of the Floor of Art. A man who wears his long green hair in a bun with one strand hanging down. He drinks beer with Roland and manages the books but slacks on cleaning. He generally uses polite speech.

The Patron Librarian of the Floor of Natural Sciences. A girl with medium-length yellow hair. A strong-willed, pessimistic tsundere. She is the smallest and youngest of the librarians and gets furious if treated like a child. She once had a twin of the same name, but they broke down completely due to overload and stopped moving.

The Patron Librarian of the Floor of Language. A woman with long red hair and a cool, big-sister vibe. She possesses combat abilities that match her fierce appearance and acts as the Library's de facto bodyguard. A heavy smoker who lights up regardless of the location.

The Patron Librarian of the Floor of Social Sciences. A blue-haired man with a laid-back personality and a love for coffee. It is said that various coffee beans are stored on the Floor of Social Sciences. He is very enthusiastic about spreading the gospel of coffee.

The Patron Librarian of the Floor of Philosophy. A woman with black hair and gold highlights who enjoys long-winded speech filled with poetic quotes and metaphors. She has a personality that enjoys tormenting and testing others, but she gets along with Angela and the other librarians, and she dotes on the Assistant Librarians, often offering them tea.

The Patron Librarian of the Floor of Religion. An elderly man with grey hair and a monocle. His hair has been grey since his youth, so he is younger than he looks. He has a bad relationship with Angela due to past conflicts, to the point of insulting Roland upon their first meeting just for being with her. However, he is reasonable and cares for Angela in his own way.