The protagonist is Yamagata Shōichirō, a reclusive novelist in his mid-seventies who has built his life around a fierce and stubborn independence. A self-proclaimed "anti-digital" holdout, he refuses to own a smartphone and lives by the motto, "I am my own doctor," rejecting regular medical checkups in favor of his own eccentric health regimens. The story begins when this carefully controlled world is shattered by a creeping physical unease he can no longer ignore. Forced to finally step into a clinic, Yamagata receives a devastating diagnosis: he has cancer.

The setting is contemporary Japan, largely confined to the intimate spaces of Yamagata's daily life—his cluttered apartment, the local streets he stubbornly navigates, and eventually the sterile rooms of the hospital where he must confront the consequences of a lifetime of avoidance. The central conflict is both internal and external. Internally, Yamagata must grapple with a disease that fundamentally undermines his lifelong philosophy of absolute self-reliance. Externally, he clashes with the modern medical establishment, its protocols, and the vulnerability that comes with being a patient.

A key narrative arc begins with the initial shock of diagnosis and his subsequent refusal to accept the implications of his illness. True to his character, he initially tries to apply his own unorthodox logic to the situation, leading to a clash with doctors and a reluctant, often cantankerous, entry into the world of surgery and treatment. The first major story beat covers the discovery of the cancer, the difficult decision to seek treatment, and the beginning of his hospital stay. A notable twist occurs when the stage of his cancer is finally revealed, forcing him to confront the true gravity of his condition and setting the stage for a more profound internal struggle. Throughout this ordeal, the only consistent presence is his mysterious young neighbor, Akemi, a hostess who appears at his door to care for him, creating a surreal and poignant counterpoint to his isolation.