Jimmy Kudo is a high school detective who helps the police solve cases. During an investigation, he is attacked by Gin and Vodka who belong to a syndicate known as the Black Organization. They force him to ingest an experimental poison called APTX 4869 to kill him without leaving evidence. A rare side-effect of the poison, however, transforms him into a child instead of killing him. Adopting the pseudonym Conan Edogawa, Kudo hides his identity to investigate the Black Organization. Later, Shiho Miyano, a member of the Black Organization and creator of APTX 4869, tries to leave the syndicate after her sister's death but is captured. She attempts suicide by ingesting APTX 4869, and like Kudo, is transformed into a child. She escapes and enrolls in Conan's school under a pseudonym, Anita Hailey. During a rare encounter with the Black Organization, Conan helps the FBI plant a CIA agent, Kir, inside the Black Organization as an undercover spy.
- Gosho Aoyama