
Kudo Shinichi/Edogawa Conan
This is the main character in the story, Kudo Shinichi. He is a famous detective who has solved many crimes and murders and pinpointed the proper culprit. He is only a high school student, adding even more to his fame. While investigating secret transactions between two men, he is found out and struck hard on the head. Two men in black feed him a dangerous poisonous chemical, which cannot be traced in the body, to keep him quiet. As Shinichi thinks he is dying, he awakens to find himself in the body of a first-grader. The poison had an unexpected side-effect, and he had shrunk into a six-year old. After consulting with his neighbor and trusty friend, Professor Agasa, they decide to keep his real identity a secret, so that nobody he knows would become a target of the men that had assaulted him. He takes on the pseudonym Edogawa Conan, and goes to live with his childhood friend Mouri Ran. Shinichi helps out her father, a detective by the name of Mouri Kogorou, to solve his cases behind the scenes, hoping that if Mouri Kogorou becomes a well-known detective, he will receive information about the men in black. Kudo Shinichi's name is based off of the fictional character Kudo Shunsaku, also from a mystery series. Shinichi gets his pseudonym from the well-known mystery authors Sir Arthur Conan Doyle and Edogawa Rampo. In North America, Kudo Shinichi is known as Jimmy Kudo.

Mouri Ran
Mouri Ran is a childhood friend of Shinichi's. When Shinichi disappears after going with her to an amusement park, she gets worried and goes to his house to see if he's home. However, instead of Shinichi, she discovers Edogawa Conan. She agrees to take care of the young boy until his parents get better, not knowing that Conan is actually Shinichi. While talking with Conan, she ends up telling him that the person she loves is Shinichi! At first, Ran has no idea that Conan could be Shinichi, but as the story progresses, she begins to see the similarities between the two. However, when she starts to get suspicious, Shinichi always thinks of a way to keep his identity a secret, and has not told Ran who he really is. Her father is a detective known as Mouri Kogorou, who used to be one of the worst detectives around. However, after Conan moved in, he has been solving the cases for Kogorou, leading him to become a famous detective. Mouri Ran's name derives from the myster writer of the Arsene Lupin stories, Maurice Leblanc. In Japanese, his name is pronounced Mou-ri-su Ru-bu-ran. In North America, Mouri Ran is known as Rachel Moore.