Junior Detective League

Detective Boys playing soccer

Junior Detective League (少年探偵団, Shōnen Tantei-dan; Literally meaning "Detective Boys Group")

Manga Chapter #17
Anime Detective Conan Episode #4
Movie The Time-Bombed Skyscraper
OVA Conan vs. Kid vs. Yaiba - The Grand Battle for the Treasure Sword!!
Appears in Anime, Manga, Game and Movie
Organization Info

Detective Boys (少年探偵団, Shōnen Tantei-dan; Viz "Junior Detective League", English TV "Junior Detective League") is a detective squad created by Conan Edogawa, Genta Kojima, Ayumi Yoshida and Mitsuhiko Tsuburaya. Genta claimed to be the leader of the gang. Ai Haibara later joined the group after attending the Teitan Elementary School. Hiroshi Agasa is their frequent guardian and also their inventor, known that he was the one who created the Detective Boys Badge. Sumiko Kobayashi their teacher is their self-proclaimed manager.


Original Detective Boys

The Original Detective Boys.

Detective Boys was originally founded when Ayumi Yoshida and Genta Kojima wanted to investigate a haunted mansion which a murder has been set there and that it has been abandoned since[1]. Ayumi asked Conan to join them after hearing about which mansion it goes about. Mitsuhiko was later been forced by Genta to join them after that Mitsuhiko told them that ghost doesn't exist[2]. After what have happened between Genta and Mitsuhiko, Ayumi cried and asks Conan again to join them which Conan officially agrees[2]. The name was officially be made in the manga at Chapter 56[3].

In the anime, the Detective Boys originally was founded by Genta Kojima[4] after finding a mysterious letter containing a code that would lead them to the treasure. This led the popularity of the Detective Boys increase by the Tokyo Metropolitan Police Force. Their popularity by Jūzō Megure increased after a murder case between twin brothers which Conan also became known by it's knowledge.

Some time later, a girl named Haibara joins the Detective Boys. Haibara became popular with Conan's class knowing that she was a cute girl and Genta also said that Haibara was more fitting than Conan[5]. Once in class many children in the class offers her a seat to sit next to her, but decided to sit next to Conan[6]. Ayumi asks Haibara to join the Detective Boys, Haibara then asks Conan if he in there too which Genta responds for him saying that he does[7].

Some time later, two adults also joins the Detective Boys. The are known as Hiroshi Agasa a good friend of Shinichi and his family and the one who develops the gadgets for Shinichi's alter ego Conan and for the Detective Boys and Sumiko Kobayashi who claims to be the manager of the Detective Boys due to her love of mystery novels.


Detective Boys, 10 Years Later

Detective Boys, 10 Years Later.

  • Conan Edogawa — Conan Edogawa is the pseudonym of prodigy detective Shinichi Kudō who have shrunk into a child by a drug from a sinister organization known as the Black Organization. He joins the Detective Boys after that Ayumi felt hurt after that Mitsuhiko didn't believe her story.
  • Genta Kojima — Genta Kojima is known as the self-proclaimed leader of the Detective Boys. Genta is a big build person and very strong for a kid. Genta's most known appearance is a yen sized bald spot on the right side of his head.
  • Ayumi Yoshida — Ayumi Yoshida was formerly the only girl in the Detective Boys group after the appearance of Ai Haibara. She is known to be a member were Mitsuhiko and Genta have a crush on, but Ayumi has a crush on Conan due to his smartness and that he protects his friends a lot of time in danger and shows that he is calm towards others.
  • Mitsuhiko Tsuburaya — Mitsuhiko Tsuburaya is the smartest kid after Conan in the Detective Boys group. Due to his smartness, Mitsuhiko sees Conan as a role model. He has shown to have crush on Ayumi but that decreases after the appearance of Ai Haibara which he shows to have a crush on.
  • Ai Haibara — Ai Haibara is the pseudonym of Shiho Miyano a former member and scientist of the Black Organization and also the one who progresses the APTX 4869 further after the unfinished project from her parents. She escapes the organization after a false promise which she discovers that Gin killed her sister Akemi Miyano. She joins the Detective Boys and became one of Conan main important person who is creating a antidote for him but it can only hold no any longer than a day. She's also discovered by some members of the Black Organization which she has become the target.
  • Hiroshi Agasa — Hiroshi Agasa is the neighbor of Shinichi Kudō also as a close friend to Shinichi's father and his mother. Agasa is also the first person who knows Shinichi's biggest secret and supports him to find a antidote to the APTX 4869. He became a main man in gadgets which he often creates very useful ones for Conan and for the members of the Detective Boys. He took in Haibara after that he found her unconsciousness in his neighborhood.
  • Sumiko Kobayashi — Sumiko Kobayashi is the teacher of the Tietain Elementary School. She is a self-proclaimed manager of the Detective Boys and is also very interested in the cases that they are involved with. Sumiko is a big mystery novel fan, mostly of Edogawa Ranpo novels.


Each member of the Detective Boy Gang have a ambition that they want to make in their career being a detective except for Conan and Haibara:

  • Genta Kojima — Genta wants to heap huge profits, which his biggest ambition is to become very rich as his career as a detective[8].
  • Ayumi Yoshida — Ayumi has the ambition to become super famous as her career as a detective[8].
  • Mitsuhiko Tsuburaya — Mitsuhiko has a dream to become a Interpol member as his career as a detective[8].


The name can be a influence of the novels from Edogawa Rampo (江戸川乱歩, Edogawa Rampo) named Detective Boys (少年探偵団, Shōnen Tantei-dan). The main character Kogorō Akechi (明智小五郎, Akechi Kogorō) is the leader of the group, but it also can be based on the novels of Edogawa Ranpo were Kogorō Akechi is involved. The group contains in total nine members counting Kogorō also as a plus which are: Yoshio Kobayashi (小林芳雄, Kobayashi Yoshio), Mayumi Hanasaki (花崎マユミ, Hanasaki Mayumi), Sōji Hashiba (羽柴壮二, Hashiba Sōji), Shōichi Katsura (桂正一, Katsura Shōichi), Hajime Shinozaki (篠崎始, Shinozaki Hajime), Ippei Noro (野呂一平, Noro Ippei), Ichirō Inoue (井上一郎, Inoue Ichirō), and Pocket Kozō (ポケット小僧, Poketto Kozō). The Detective Boys gang is known to have only kids in the group that assist the Detective Kogorō with many complicated cases. The organization was originally been created by Yoshio Kobayashi which he is the head of the Detective Boys and also the first apprentice of Kogorō. After that Kogorō got kidnapped by his nemesis Phantom of Twenty Looks (怪人二十面相, Kaijin Nijūmensō) after that he saved Kogorō from the phantom. The Detective Boys soon extended into information bringing group.


  • Genta has a habit to refer Conan as his apprentice to show of to people due to Conan's smartness.
  • The name "Detective Boys" wasn't known until Chapter 56 on the chapter cover.


  1. Detective Conan Manga; Chapter 17, page 2
  2. 2.0 2.1 Detective Conan Manga; Chapter 17, page 5
  3. Detective Conan Manga; Chapter 56, page 1
  4. Detective Conan Anime; Episode 4
  5. Detective Conan Manga; Chapter 176, page 3
  6. Detective Conan Manga; Chapter 176, page 5
  7. Detective Conan Manga; Chapter 176, page 8
  8. 8.0 8.1 8.2 Detective Conan Manga; Chapter 56, page 5