Ron Kamonohashi

Shueisha also simultaneously publishes the series in English on the Manga Plus online platform. An anime television series adaptation produced by Diomedéa aired from October to December 2023. A second season premiered in October 2024.

The series focuses on the adventures of Ron Kamonohashi, an eccentric private detective, and Totomaru Isshiki, an unskilled police officer, as they solve crimes together. Five years ago, Ron was the top student at the Detective Training Academy Blue. However, after being found responsible via temporary insanity for a deadly incident known as the "Bloody Field Trip", his detective license was revoked and he was expelled. Unable to fulfill his only love of solving mysteries, Ron has lived in isolation since. When Totomaru seeks his help on a case, the two form a partnership where Totomaru takes the credit for the cases that Ron solves.

Ron Kamonohashi (鴨乃橋 ロン, Kamonohashi Ron) Voiced by: Yōhei Azakami Portrayed by: Yuta Kishimoto A sixth-generation descendant of Sherlock Holmes, and a ninth-generation descendant of James Moriarty. His detective license was revoked five years ago following the "Bloody Field Trip", an incident he cannot remember. Whenever he hears a murderer confess their crime, Ron enters an uncontrollable state where he pressures and convinces them to kill themselves. Totomaru Isshiki (一色 都々丸, Isshiki Totomaru) Voiced by: Junya Enoki Portrayed by: Yutaka Nozaki A police detective in the Metropolitan Police Department who gains some renown by taking credit for the cases that Ron solves. Ron calls him by the nickname "Toto" (トト). Amamiya (雨宮) Voiced by: Yoko Hikasa Portrayed by: Haruna Ishii Totomaru's boss in the Metropolitan Police. Although usually cold and serious, she has a crush on Ron, whom she thinks is named "Kamoo" (鴨夫). Mofu Usaki (卯咲 もふ, Usaki Mofu) Voiced by: Nao Tōyama Portrayed by: Marina Tanoue A renowned neurosurgeon who is extremely clumsy outside the operating room and is always wearing bandages due to her injuries. She concocts a combination of medicines to suppress Ron's "culprit-killing" syndrome, but there are side effects. Omito Kawasemi (翡翠 臣疾, Kawasemi Omito) Voiced by: Jun Fukuyama Portrayed by: Hiroki Suzuki A pedantic detective from the Aichi Prefectural Police. He has the highest number of solved cases in the entire country and is an old colleague of Amamiya. Chikori Monki (門季 チコリ, Monki Chikori) Voiced by: Konomi Kohara A crime reporter who often helps Totomaru and Ron with research and information gathering. She greatly admires Totomaru and dislikes Ron. Elmer Stingray (エルマー・スティングレイ, Erumā Sutingurei) An American who transferred to Blue Academy three days before the "Bloody Field Trip" and claims to have been Ron's friend, although Ron does not remember him. He is revealed to be an assistant to the Holmes family, specifically to Ron's mother, who views him as an adopted son.

The Detective Training Academy Blue (探偵養成学校BLUE) in England is the world's most prestigious academy for training detectives. Spitz Feier (シュピッツ・ファイア, Shupittsu Faia) Voiced by: Taku Yashiro Portrayed by: Ryōma Baba The tracking instructor at Blue, who is sent to investigate whether Ron is violating his detective ban. However, his actual goal is to have Ron help him find his missing brother. Spitz befriends Ron and Totomaru and continues to assist them on various cases. Fin Fennec (フィン・フェネック, Fin Fenekku) Voiced by: Megumi Han The locked room instructor at Blue and one of less than 10 people in the world who have an S-rank detective license. Shachi (シャチ) Fin's bodyguard and a graduate of Blue. He attended the academy at the same time as Ron. He is revealed to be the M. Family's informant at Blue. Hirsch (ヒルシュ, Hirushu) Voiced by: Kenjiro Tsuda The anatomy instructor at Blue. He has been a suspect in 15 murder cases, with one of these instances being the reason he was demoted to A-rank detective. Emme Emmerich (エメ・エメリッヒ, Eme Emerihhi) Voiced by: Kikuko Inoue The principal of Blue and a friend of Ron's parents. She informs Ron of the M. Family's involvement in the Bloody Field Trip incident, though discretely due to there being an M. Family informant at Blue. John Grizzly (ジョン・グリズリー, Jon Gurizurī) Voiced by: Kazuhiro Yamaji Portrayed by: Shūhei Izumi The closed circle instructor at Blue. Night Bran Jr. (ナイト・ブラン・Jr., Naito Buran Jr.) The number one student at Blue, son of a vice-chairmen of the World Detective Alliance, and a descendant of the first principal of Blue. Alyssa Beaumont (アリッサ・ボーモント, Arissa Bōmonto) The number two student at Blue, who wears a headband with rabbit ears on it. Hutter Horn (ハッター・ホルン, Hattā Horun) A top student at Blue, who attends thanks to a scholarship under John Grizzly. Marsh Leipley (マーシュ・レプレー, Māshu Repurē) A top student at Blue.

The Moriarty Family (モリアーティ家), more commonly referred to as the "M. Family" (M家), is a legendary crime syndicate and the archenemy of the Holmes detective family. Tiger Dan (タイガ・ダン, Taiga Dan) Voiced by: Takehito Koyasu Milo's uncle, whose real name is Daniel Moriarty (ダニエル・モリアーティ, Danieru Moriāti). Winter Moriarty (ウィンター・モリアーティ, Uintā Moriāti) Voiced by: Yumiri Hanamori Portrayed by: Mizuho Habu The fourth child of the M. Family who specializes in disguises. After failing at a mission, Milo has an assassin shoot Winter, but then has doctors nurse her back to health as she survives the attack. After recovering, Winter splits from Milo, whom she never forgave for killing their younger sister Alice. Milo Moriarty (マイロ・モリアーティ, Mairo Moriāti) Voiced by: Yoshitsugu Matsuoka Portrayed by: Yoshihide Sasaki The eldest child and head of the M. Family. He killed his younger sister Alice in order to earn that position. After he loses to Ron, Milo is attacked on the orders of the "new boss" of the family. This is later revealed to be Alice, who survived because she tampered with the gun before Milo shot her. "Disappointed" that Milo showed emotion by hugging her and crying after the shooting, Alice plotted to steal the M. Family away from him once she turned 17. Alice Moriarty (アリス・モリアーティ, Arisu Moriāti) The youngest child of the M. Family. Initially believed to be dead, Alice first appears in the series under the guise of "Billy Za Gojila" (ビリー・ザ・ゴジラ, Birī Za Gojira), nicknamed "Billy Goji", a top student at Blue who always has various animals on her. She perpetrates a series of murders at Blue, before escaping custody as her true identity is revealed.

Kei Moore Kikuma (菊間・ケイ・ムーア, Kikuma Kei Mūa) Director of the Japanese Branch of the World Detective Alliance, an underclassman of Ron at Blue, and the son of Kiku, a police officer and friend of Ron.

Ron Kamonohashi: Deranged Detective, written and illustrated by Akira Amano, began its bi-weekly serialization in Shueisha's online magazine Shōnen Jump+ on October 11, 2020. The series ended its first part on April 30, 2023, with the second part beginning on June 4. The second part concluded on July 6, 2025. Shueisha has collected its chapters into individual tankōbon volumes. The first volume was released on February 4, 2021. As of October 3, 2025, nineteen volumes have been released. The series has been licensed for simultaneous publication in North America as it is released in Japan, with its chapters being digitally launched in English by Shueisha on its Manga Plus service.

An anime television series adaptation was announced on December 18, 2022. The series is produced by Diomedéa and directed by Shōta Ihata, with scripts written by Wataru Watari, character designs handled by Masakazu Ishikawa, and music composed by Yo Tsuji. The series aired from October 2 to December 25, 2023, on Tokyo MX, AT-X, and other networks. The opening theme song is "Ikenai Fool Logic" (いけない fool logic) by Unison Square Garden, while the ending theme song is "Lipsync" (リップシンク) by Hockrockb. Following the airing of the final episode, a second season was announced. It aired from October 7 to December 30, 2024. The opening theme song is "Feedback o Narashite" (フィードバックを鳴らして; "Playing Feedback"), by Humbreaders, while the ending theme song is "Labyrinth" (ラビリンス, Rabirinsu), by Hockrockb. Crunchyroll streamed the series outside of Asia under the title Ron Kamonohashi's Forbidden Deductions. Medialink licensed the series in South, Southeast Asia, and Oceania (except Australia and New Zealand) and is streaming it on its Ani-One Asia YouTube channel for its Ultra subscribers.

A stage play adaptation ran from November 1–4, 2024, at the Nippon Seinenkan Hall in Tokyo, and on November 9 and 10 at the Sankei Hall Breeze in Osaka. It was written and directed by Keita Kawajiri, with music composed by Futoshi Arai.