Edogawa Rampo, already known as a successful detective and horror writer, gained an assignment writing for
Shōnen Club, a magazine aimed at young children. Government regulations and societal norms meant that many of Rampo's normal plot elements were off the table, such as putting the protagonist children in direct danger. Rampo decided to create a villain related to his existing world and created a new rival for his detective character
Kogoro Akechi. Rampo based his new character on
Arsène Lupin, a gentleman thief. He originally intended to name the character Kaitō Nijū Mensō ("The Phantom Thief with Twenty Faces"), as Lupin was referred to as a kaitō, but this was ruled out by his editors. "Kaijin" ("Strange Person", "Fiend") was approved, however, giving him his published name. He makes his first appearance in
The Fiend with Twenty Faces published in 1936, the first installment of Rampo's "The Boy Detectives Club" series. The titular antagonist threatens Tokyo, but with the country's greatest detective Kogorō Akechi away on overseas business, it is up to his 10-year old assistant Kobayashi Yoshio and the Boy Detectives Club (
Shōnen Tantei-dan) to save the day. In these stories, Akechi is generally busy in the first half, Twenty Faces will either steal or threaten to steal some valuable item, the kids will come close to foiling him, and Akechi will dramatically return to foil the plan and ensure the kids were never overly threatened. ==In other media==