The story opens with Hajime Kindaichi at forty-four years old, now a father and the operator of the tiny, financially struggling Kindaichi Detective Agency. He left his corporate job after becoming a parent, hoping to devote more time to raising his son, Tsukumo, while also pursuing a career as a private investigator. His wife, Miyuki, works as a flight attendant and remains the household’s primary breadwinner, a reality that weighs on Hajime and fuels a recurring anxiety about failing his family.

The series follows Hajime as he juggles the mundane tasks of a small-time detective—surveillance for infidelity cases, lost pet searches—with the far more dangerous murder cases that inevitably find him. His first major case, the Private Detective Murder Case, begins when a mysterious figure calling themselves the Client offers an unusually large fee to search an abandoned inn for an avocado-shaped badge. Five detectives, including Hajime and his son Tsukumo, gather at the site, and before long one of them is killed. Hajime must use his inherited deductive talents in a closed-circle setting, with Tsukumo’s innocent observations often providing unexpected leads.

Later arcs deepen the social commentary. The Mummy Diva case involves a hospital where a vengeful figure targets a plastic surgeon, exposing medical malpractice and hidden grudges. Hajime’s perspective as a father colors every investigation: he is more cautious, more attuned to the emotional fallout of crimes, and more driven by a need to protect his son from the horrors he uncovers. His relationship with Miyuki is portrayed with realism—she supports him but is not shy about the financial strain, and their marriage is tested by his unpredictable work.

The setting is a modest apartment that doubles as his office, a far cry from the grandiose locales of his youth. Tsukumo, a first-grade boy with a sharp eye, frequently accompanies his father on cases, and their bond becomes the emotional core of the narrative. Hajime’s growth is measured not only in solved mysteries but in his evolving understanding of responsibility, sacrifice, and the value of the quiet, everyday moments he now fights to protect.