An elementary school student with reasoning skills that rival any adult's, but his true identity is high school detective Shinichi Kudo. After witnessing a secret transaction by a mysterious organization, he was forced to drink an experimental poison intended to kill him, which instead shrunk his body. To hide the fact that Shinichi is still alive, he goes by the name Conan Edogawa and lives at the Mouri Detective Agency.

Her real name is Shiho Miyano. Like Conan Edogawa, her body has shrunk, and she is currently enrolled in Teitan Elementary School. She is a former scientist for the Black Organization, where she was known by the code name Sherry.

Ayumi Yoshida: The heroine of the Junior Detective League, recognizable by her bob cut and headband. She is the one who invited Conan and Haibara to join the group and was the only girl in the league until Haibara joined. 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, and he has an older sister in middle school named Asami. While not on the level of Conan or Haibara, he possesses a wealth of knowledge far beyond a typical first grader. Genta Kojima: The self-proclaimed leader of the Junior Detective League. A cheerful and strong mood-maker. He has a massive build for a first grader, a triangular head, and a small bald spot. He loves to eat, especially eel bowls.

Juzo Megure: An inspector who leads the First Investigation Division of the Metropolitan Police Department. His stout build reflects his depth of character; he is a reliable boss trusted by his subordinates. He prioritizes saving lives when hostages are involved and commands the scene with a strong sense of responsibility. Ninzaburo Shiratori: Formerly Inspector Megure's subordinate as an Assistant Inspector, he has already been promoted to Inspector. He is a top-tier elite within the MPD on the fast track to promotion. Wataru Takagi: Inspector Megure's subordinate. His mild-mannered personality makes him easy for Conan and the others to rely on. He has feelings for Detective Sato, who is two years his senior. Miwako Sato: The only woman in the First Investigation Division. She excels in martial arts and marksmanship, performing at the level of an action star. Though beautiful, she is friendly and approachable, boasting immense popularity even among the tough-faced detectives of the division.

Wearing a black knit cap and a white mask (pretending to have a cold and coughing). He wears a calm-colored coat and jacket, mostly in black. He is on the bus as a passenger, tracking the Organization.

An English teacher at Teitan High School who approached Vermouth while the latter was disguised as Dr. Araide. During this time, she pretends to be poor at speaking Japanese.

Bus Hijackers: Square-faced man (Leader): Real name unknown. The leader carrying a handgun. Wearing ski gear. Long-faced man (Accomplice): Real name unknown. A man with a violent temperament. Wearing ski gear. Elderly man with glasses wearing a hearing aid in his left ear. Female passenger sitting near the rear seats. Aramaki: The bus driver taken hostage.

An alumnus of Teitan High School, which Shinichi and Ran attend. He graduated at the top of his class from Toto Medical University and became a doctor at the Araide Clinic run by his father, Yoshiteru. He visits Teitan High as the school doctor and also serves as a temporary coach for the basketball club he once belonged to. (In this scenario, Vermouth is disguised as Araide.)

A genius inventor living next door to the Kudo residence. His full name is Hiroshi Agasa, but Conan and the others call him "Professor" as a title. He is an ally to Conan and Haibara and one of the few people who knows their secret. He often takes the Junior Detective League on camping trips and picnics.