Tucked away in a quiet corner of Kamakura, a small used bookstore called Biblia Koshodō serves as the stage for a series of quiet, bookish mysteries. The owner, Shioriko Shinokawa, is a strikingly beautiful young woman whose extreme shyness makes everyday conversation a struggle. Yet when it comes to old books, she transforms completely: her knowledge is encyclopedic, her memory sharp, and her ability to read the hidden stories embedded in worn pages is almost uncanny. Every book that passes through her hands carries traces of its previous owners, and Shioriko has a gift for unraveling the secrets those traces hold.

The story opens when a young man named Daisuke Gōra walks into the shop. He has grown up with a kind of phobia of books, rarely reading at all, but he has inherited a complete, autographed set of Natsume Sōseki's works from his grandmother. He wants an appraisal, and his arrival sets the plot in motion. Drawn into Shioriko's orbit almost against his will, Daisuke soon finds himself working as a part-time employee at the bookstore. Through his eyes, readers encounter a procession of unusual customers: a book flipper trying to recover a stolen volume, a woman seeking a rare edition tied to her family history, a man with a mysterious connection to Shioriko's missing mother, and others whose lives are entangled with the books they bring.

The stories are self-contained but gradually interweave into larger arcs. Early chapters focus on individual mysteries: a signed copy of a classic novel reveals a hidden romance; a slim volume of poetry holds a clue to a decades-old disappearance; a rare science fiction paperback connects strangers across generations. As the series progresses, deeper threads emerge. Shioriko's past becomes a central puzzle, especially the circumstances of a fall that hospitalized her before the story began, an incident she eventually confesses was not an accident but an attack. Daisuke's own history with books and his family also comes into focus, and the relationship between the two protagonists deepens from cautious professional distance to mutual trust and affection.

The setting is essential to the atmosphere. Kamakura, an old capital of Japan, provides a backdrop of temples, narrow lanes, and a sense of history that mirrors the aged books at the heart of each case. The bookstore itself, Biblia Koshodō, is a small, cluttered space where the scent of old paper and leather bindings hangs in the air, and where every shelf seems to hold a story waiting to be told.

The narrative is structured around two major story blocks that originate in the source light novels. The first block, centered on Shioriko herself, follows her and Daisuke as they solve mysteries tied to real, often rare editions while also confronting the secrets surrounding Shioriko's family and the attack on her life. This arc reaches a major emotional and narrative climax when Shioriko and Daisuke formally acknowledge their bond, bringing a sense of closure to that phase of the story. After that, the focus shifts to a new generation: the second block introduces the couple's daughter, Tobiko, who inherits her mother's talent for deciphering the stories hidden in old books. The setting remains the same bookshop in Kamakura, but the perspective and cast of characters expand, allowing new mysteries to unfold while still carrying the legacy of the earlier tales.

Throughout, the series treats each real, named book with respect and care, using its history, author, and physical condition as the raw material for human-centered puzzles. The mysteries are gentle, driven by emotion and memory rather than violence, and the resolution of each case tends to bring understanding or reconciliation to the people involved. The bond between books and their owners is the true subject, and Shioriko, whether as a shy young shopkeeper or later as a mother and mentor, acts as the interpreter of that bond.