Meitantei Conan 

(名探偵コナン) Jimmy Kudo is a 17-year-old high school prodigy who frequently helps the police to solve cases.During an investigation, he is attacked by two criminals, codenamed Gin and Vodka, from the syndicate known as the Black Organization. They force him to ingest an experimental poison, APTX 4869, and leave him to die. A rare side-effect of the poison, however, transforms Kudo's body into that of a child instead of killing him. 

Adopting the pseudonym Conan Edogawa, Kudo hides his identity to investigate the Black Organization.He pretends to be a child until he can find enough evidence to apprehend the syndicate, after which he can then safely find and administer a cure for his current condition. Edogawa enrolls at Teitan elementary school and forms the Junior Detective League with three other children in his class: Amy Yoshida, Mitch Tsuburaya, and George Kojima.To further cover up his activities, he moves in with his childhood friend Rachel Moore, whose father, Richard, works as a private investigator.Kudo continues to solve criminal cases as Conan, but usually poses as Richard Moore with the help of special gadgets invented by his neighbor and friend, Hiroshi Agasa. 

Shinichi Kudo (工藤 新一)

During one of his investigations, he is attacked and forced to take an experimental poison by a member of the Black Organization. The drug was supposed to kill him, but due to a rare side-effect, he was inadvertently shrunk back to his childhood body.[In order to keep his true identity a secret, he now goes under the alias Conan Edogawa  and pretends to be a real child to throw off suspicion while he secretly solves many cases and looks for clues about the organization.

Ran Mori (毛利 蘭)

  She is a highly skilled martial artist with a black-belt in Karate and is well-trained by her father in Judo.

She is also very skilled in all forms of house chores, including sewing and cooking, and is astonishingly lucky at games of chance, having never been known to lose.