He first appeared in the story "The D Slope Murder case" in 1925 and continued to appear in stories for a quarter of a century. Akechi is the first recurring detective character in Japanese fiction and is clearly inspired by Arthur Conan Doyle's Sherlock Holmes.
Like Holmes, Akechi is a brilliant but eccentric detective who consults with the police on especially difficult cases. He is a master of disguise and an expert at judo whose genius lets him solve seemingly impossible cases. Also like Holmes, Akechi makes use of a group of young boys to gather information. His version of the Baker Street Irregulars is known as the Detective Boys (少年探偵団 Shounen Tantei-dan, lit. Boy Detectives Club). Akechi smokes Egyptian cigarettes when he is thinking about a case.
Kogoro Akechi is a tall, handsome man with heavy eyebrows who dresses well, although in earlier stories he always wore a dirty green yukata and had messy hair. He is married to a woman named Fumiyo (文代 ) and has an adopted son, Yoshio Kobayashi (小林 芳雄 Kobayashi Yoshio), the leader of the Detective Boys. Kobayashi often plays an important part in solving cases. Like his mentor, he is an expert at disguise and is especially adept at posing as a young woman. Aside from these relationships little is known of the detective's personal life, which always takes a back seat to the mystery in his adventures.
Detective Akechi's most frequent foe is the infamous Kaijin Nijuu Mensou (怪人二十面相 Fiend with Twenty Faces). The Fiend is a non-violent criminal with an infallible gift for disguise who steals to demonstrate his brilliance rather than out of need for money. He and Akechi have a mutual respect in the stories.
The Akechi stories are based mainly in the detective's home city of Tokyo, though some move the action to the Japanese countryside. The stories often feature supernatural and erotic overtones, though not so much as Rampo's other fiction.
There are more allusions to Akechi than any other detective in the manga. The main ones are:
- Kogoro Mouri: Has the same kanji for Kogoro as Akechi.
- Detective Boys: The name chosen by Conan and his friends for their school detective agency.
- Fumiyo Edogawa: An alias used by Yukiko Kudo, taken from Akechi's wife.
- Tomoaki Araide: The kanji for "Akechi" (明智) are rearranged and used for "Tomoaki" (智明).
- Sumiko Kobayashi: Although it is said she is named after a friend of Gosho Aoyama's, the name Kobayashi could be taken Akechi's adopted son. Kobayashi-sensei is also a fan of Rampo Edogawa.
- Fiend with 200 Faces: A mystery game created by Kobayashi-sensei for her class, based on Akechi's rival, the Fiend with 20 Faces.