Huey receives an immense quantity of books and his grandfather's historic mansion as an inheritance. However, in order to keep the mansion, he must take on the responsibility of being the proprietor of the "Bibliotheca" as well. In his exploration of the property, he stumbles upon a basement filled with literature and meets a mysterious girl named Darian in front of the entrance to the "Bibliotheca of Dantalion." Darian is dressed in dark attire and guards the library's entrance, which is solely accessible by unlocking her large lock. It contains forbidden books referred to as the "Phantom Books."
