A 7-year-old boy. His true identity is Shinichi Kudo, a high school detective whose body was shrunk by a mysterious organization. He strictly hides his identity from everyone except Professor Agasa and Haibara. He possesses incredible deductive reasoning skills just like his original self, but he is tone-deaf.

A 7-year-old girl. She used to work for the organization that shrunk Shinichi, but she is currently on the run after taking the drug and shrinking herself. Though she has a cold and prickly personality, she is gradually opening up while spending time with the Junior Detective League. Her true identity is 18-year-old Shiho Miyano. She and Conan are partners.

A 7-year-old girl and Conan's friend. Like most children her age, she is innocent and cheerful. As a side note, she seems to have a crush on Conan.

A 7-year-old boy and Conan's friend. While he acts like any other child his age, he occasionally shows surprising insight.

A 7-year-old boy and Conan's friend. He is rough and reckless, but has a strong sense of justice.

A 26-year-old woman and the homeroom teacher of Class 1-B, which Conan and his friends belong to. She has a warm personality and takes good care of her students.

A 16-year-old high school student and Kogoro's daughter. She is Shinichi's childhood friend and acts like an older sister to Conan, who is Shinichi's current form. She is usually kind, but when she gets angry, she doesn't hesitate to show off her karate skills. She doesn't know Conan's true identity yet, though Conan has acted carelessly enough to almost get caught by her several times.

A 39-year-old man, Ran's father, and Conan's guardian. He is a detective, but... he's quite a blunderer. However, he can be serious when the situation calls for it.

A 52-year-old man and an inventor. He has a personality full of childlike wonder. He is the only person in the story who knows the true identities of both Conan and Haibara. He rescued Haibara after she escaped from the organization and has been letting her live at his mansion.