A prequel original video animation split into two parts, titled "Episode 00", was released on December 22, 2016.

The encounter between the two eventually leads them to the connection between the criminal nicknamed "Fiend with Twenty Faces" (Kaijin Nijuu Menso) and Kogoro Akechi.

[2] The anime production, inspired from The Boy Detectives Club (1937) and The Fiend With Twenty Faces (1936) novels written by Edogawa Ranpo, was unveiled by TMS Entertainment on June 1, 2016, with the anime's official website listing the series' main staff, main cast, synopsis and broadcast dates.

[4] A prequel OVA written by Gō Zappa and Takeshi Miyamoto, titled "Episode 00", was released on December 22, 2016.

[13] Binta's manga adaptation began serialization in Kodansha's July 2016 issue of Magazine Special on June 20, 2016.