Kogoro Mori is a former police detective who retired from the Tokyo Metropolitan Police Department to open his own private investigation business, the Mouri Detective Agency, which also serves as his home in Beika Town. He attended Teitan High School alongside his future wife Eri Kisaki and later graduated from Beika University, where he was the ace of the judo team. After university he became a police officer working under Inspector Megure, where he was known as an excellent marksman but not a particularly strong investigator. He left the force around the time he and his wife separated, an event connected to an incident in which he grazed her leg with a bullet to save her from a hostage situation. Eri, a successful lawyer, moved out soon after, and the two have never officially divorced, remaining estranged for roughly ten years. Kogoro now raises their daughter Ran as a single father.

Kogoro is lazy and often spends his days lounging in his office drinking beer and watching television, showing interest in cases only when the client is an attractive woman. He drinks heavily and smokes frequently, and he is known for flirting with other women despite being married, a habit that embarrasses Ran and contributes to the strain in his marriage. He has an inflated sense of his own importance as a detective and rarely questions why he keeps losing consciousness at crime scenes and waking up to find the case solved. During his ordinary waking hours his deductions tend to be hasty and incorrect, following only the most obvious clues and frequently falling into a culprit’s trap. The police, including Inspector Megure, often regard him as unreliable while he is awake and eagerly await the appearance of his sleeping alter ego.

Despite these flaws, Kogoro possesses a strong sense of justice and a genuine protective instinct toward those he cares about. When a case involves his ex-wife or his daughter, his entire demeanor changes: he becomes focused, professional, and capable of sound logical reasoning. On such occasions he demonstrates improved deductive skills and a keen understanding of interpersonal relationships, sometimes seeing connections that even Conan overlooks. He is a highly skilled martial artist, having been the judo champion at university, and he regularly uses his signature shoulder throw to subdue criminals. He is also an expert marksman from his days as a police officer.

Kogoro’s role in the story is that of Conan Edogawa’s unwitting public front. After the high school detective Shinichi Kudo is forced into a child’s body and assumes the alias Conan Edogawa, the scientist Hiroshi Agasa arranges for Conan to live with Kogoro so that the boy can secretly continue his investigations. Conan routinely tranquilizes Kogoro with a stun-gun wristwatch and uses a voice-changing device to impersonate him, delivering brilliant deductions that make Kogoro appear to solve cases while unconscious. This pattern quickly earns Kogoro the nickname Sleeping Kogoro and a reputation as a master detective, leading the police to call on him regularly for cases they cannot crack. Kogoro himself takes full credit for these feats, never suspecting that the real detective work is being done by the child living under his roof.

His key relationships define much of his character. He genuinely loves his daughter Ran, though he often frustrates her with his drinking, his laziness, and his behavior around women. He still carries feelings for his estranged wife Eri, and on rare occasions the two share moments of mutual affection, but their pride and his ongoing flirtatiousness prevent reconciliation. He has a complicated relationship with Conan, whom he initially sees as an annoyance but gradually comes to tolerate and even care for, though he remains unaware of Conan’s true identity. He maintains a close professional connection with Inspector Megure, his former superior, who frequently works alongside him on cases. He is also an obsessive fan of pop idol Yoko Okino, filling his office and bedroom with her merchandise and never missing her television appearances.

Over the course of the story, Kogoro develops from a struggling private detective barely making ends meet into a nationally famous figure hailed as a genius sleuth. This fame is entirely accidental, built on Conan’s manipulations, but it occasionally pushes Kogoro to take his work more seriously. While his fundamental laziness and vanity remain, moments of genuine insight and selfless courage show a more capable and honorable man beneath the surface. He remains separated from Eri, but their connection endures, and Ran continues to hope for a reunion. Kogoro’s combination of comic flaws, hidden competence, and steadfast loyalty to his family makes him a central and enduring presence in the series.