In the quiet town of Kamakura, a small used bookstore called Biblia Koshodō sits tucked away on a side street. The shop is run by Shioriko Shinokawa, a strikingly beautiful young woman whose extreme shyness makes ordinary conversation a challenge. When it comes to old books, however, her timidity vanishes. Her knowledge of rare editions, author signatures, and the history of printed works is encyclopedic, and she possesses a remarkable talent for solving the mysteries hidden within the volumes that pass through her hands.

The story begins when Daisuke Gōra, a young man carrying a deep-seated trauma from a childhood incident with his grandmother, brings a set of the complete works of Natsume Sōseki to the store for appraisal. The collection appears to be autographed, and he hopes to have its value assessed. Daisuke has grown up essentially unable to read books due to a phobia, but his encounter with Shioriko changes his path. As she explains the true story behind the signature and the books themselves, Daisuke finds himself drawn into a world he had always feared.

Each narrative arc centers on a different rare or unusual book brought in by a customer. These volumes carry secrets—forgotten ownership histories, hidden messages, forgeries, or connections to past crimes. Shioriko pieces together the clues embedded in the books’ physical condition, marginal notes, and provenance, revealing the human dramas that surround them. Along the way, Daisuke becomes her assistant and, gradually, begins to overcome his fear of reading through her infectious passion.

The setting of Biblia Koshodō itself is a character in its own right, a cozy, slightly dusty space filled with aging paper and the quiet atmosphere of a secondhand bookshop in Kamakura. The relationship between Shioriko and Daisuke deepens across the arcs, moving from a purely customer-and-shopkeeper dynamic to one of mutual trust and unspoken affection. The series blends gentle mystery with bibliophile detail, exploring how books carry the stories not only of their authors but of every reader who has owned them.