Born Tarou Hirai on 21 October 1894, in Nabari-machi, Naga-gun, Mie Prefecture, Japan, he was arguably the most famous japanese author of mystery stories for young boys. He chose his nom de plume in honor of Edgar Allan Poe, whom he idolized, and whose name could be written thusly in katakana: Edoga (w)aran po. He died in 1965.
Amongst his most famous books is The Mysterious Man with Twenty Faces Masks (Kaijin Nijumenso), revolving around detective Akechi Kogoro and his rival, the man with the 20 face masks, a thief who makes use of his ability to be anyone he chooses to be. Several movies have been made out of the series of stories revolving around these characters, the latest a made-for-TV movie starring Masakazu Tamura and (Beat) Takeshi Kitano aired recently on TBS.
He is in turn paid homage to in the popular anime series Detective Conan's main character Conan Edogawa. There is also a movie, The Mystery of Ranpo, released 1994 that revolves around him and his mysteries.
Thanks to mkb for the info about the movie.