Anne Mihara, a high school student, is staying with a host family during her summer vacation at a private library, known as the “Book House,” located in the suburbs of Sapporo. Breaking the rules announced to her by the unfriendly library owner, Sage, Anne wanders into the library in the middle of the night. There, she finds herself in a desolate underworld, a “library labyrinth” where “phantoms of stories” wander about! Anne is assigned as the librarian of the labyrinth and is ordered to “restore the labyrinth by having as many people as possible read the books in the library.

In an old house surrounded by beautiful nature, the “story” of a girl with no self-confidence begins to change color.