He has brown hair and wears square glasses. He always wears a bowtie, which he uses to mimic others' voices. The watch on his wrist is actually a tranquilizer gun; when Kogoro makes a wrong deduction, Conan puts him to sleep and solves the case in his place using the bowtie. His true identity is the high school detective Shinichi Kudo. After being forced to take a drug by a mysterious organization, his body shrank. He came up with a name on the spot using book titles and is now living at the Mori Detective Agency. He was Ran's boyfriend back when he was Shinichi.

He runs the Mori Detective Agency and is Ran's father. He often makes absurd deductions and is constantly knocked out by Conan's tranquilizer gun, allowing Conan to solve the cases. Unaware of the truth, people call him 'Sleeping Kogoro' and find his ability to solve crimes while asleep fascinating. His wife is the lawyer Eri Kisaki. He has a bit of a short-tempered personality.

Kogoro's daughter and Shinichi's girlfriend from before he shrank. She is quite beautiful and has many friends. She frequently worries about Conan and Kogoro, and sometimes unintentionally provides clues that help solve the cases.

He looks remarkably like Shinichi Kudo and is a rival to both Conan and Kogoro. He uses elaborate tricks to steal glittering jewels without anyone noticing. Ran often finds herself smitten by his handsome looks. While he isn't easily caught by weak attacks, he occasionally falls for Conan's clever traps. His true identity is a high school student, though no one knows this yet. He has a sly and playful personality.