An elementary school student with deductive reasoning skills that rival any adult's. His true identity is the high school detective Shinichi Kudo. After witnessing a secret transaction by a mysterious organization, he was forced to drink an experimental poison to silence him, which resulted in his body shrinking. To hide the fact that Shinichi is still alive, he took the name Conan Edogawa and lives as a lodger at the Mouri Detective Agency.

Shinichi Kudo's childhood friend and the daughter of private detective Kogoro Mouri and lawyer Eri Kisaki. Since her parents are living apart, Ran lives with her father and handles all the household chores. She is a reliable girl and a skilled cook. She treats Conan, who lives with them, like a younger brother.

A former police officer turned private detective who runs his own agency in Beika City. He is Ran Mouri's father. His detective business was struggling due to his mediocre deductions, but after Conan began solving cases behind the scenes on his behalf, the reputation of "Sleeping Kogoro" became firmly established. He is an expert marksman with a handgun.

Her real name is Shiho Miyano. Like Conan Edogawa, her body has shrunk, and she is currently enrolled at Teitan Elementary School. She is a former scientist for the Black Organization. She developed APTX 4869, the drug that caused the shrinking, but she is now researching an antidote under the protection of Professor Agasa.

Ayumi Yoshida: The heroine of the Junior Detective League, recognizable by her bob cut and headband. She is the one who invited Conan and Ai to join the group. Mitsuhiko Tsuburaya: Polite and always uses formal speech. He is a gentlemanly, intelligent, and sensible member of the group. Both of his parents are teachers. While not on the level of Conan or Ai, he possesses a wealth of knowledge far beyond a typical first grader. Genta Kojima: The self-proclaimed leader of the Junior Detective League. He is a cheerful and strong mood-maker. He has an unusually large build for a first grader, a triangular head, and a small bald spot. He loves to eat, especially eel bowls.

A genius inventor who lives next door to the Kudo residence. His full name is Hiroshi Agasa, but the children call him "Professor." He is an ally to Conan and Ai and one of the few people who knows their secret.

An inspector who leads the First Investigation Division of the Tokyo Metropolitan Police Department. His stout build reflects his big-hearted nature, and he is highly trusted by his subordinates as a reliable boss. He prioritizes saving lives in hostage situations and leads the scene with a strong sense of responsibility. However, his deductive skills and marksmanship are somewhat lacking.

The only female officer in the First Investigation Division. She excels in martial arts and marksmanship, performing at the level of an action star. Although beautiful, she is friendly and approachable, boasting immense popularity even among the tough detectives of the division. She is in a romantic relationship with Detective Takagi.

Inspector Megure's subordinate. His gentle personality makes him someone Conan and the others find easy to rely on. He had feelings for Detective Sato, who is two years his senior, and finally managed to win her heart. However, he now spends his days being glared at by the tough detectives who watch over the popular Sato.

He was Inspector Megure's subordinate during his time as a Detective Sergeant, but has already been promoted to Inspector. He is a top-tier career track officer in the Metropolitan Police Department. He is in a mutual relationship with Ms. Kobayashi, Conan's homeroom teacher.