@A popular detective story for boys, Kaijin Nijû Mensô first appeared in Shônen Club [Boys' Club] in 1936. The author, Edogawa Rampo, wrote his first novel in 1923. Kaijin Nijû Mensô is his first story for children. This volume was published just after its serialization was over. Together with the illustrations by Kobayashi Hidetsune, this book gained great popularity.
@The story is as follows: at that time, a Mysterious Man with twenty faces, a thief very good at disguises, terrifies people in Tokyo. Akechi Kogorô, a detective, and Kobayashi Yoshio, his boy assistant, work hard to arrest him. The Mysterious Man tries to rob the Hashiba family of their jewelry. Kobayashi, Hashiba Sôji (a boy of the Hashiba family), and their Troop of Boy Detectives (Shônen Tantei Dan) overcome obstacles such as Kobayashi's imprisonment by the Mysterious Man, and help Akechi catch the villain.
@This book is followed by other stories in which Kobayashi plays an active part, like "Shônen Tantei Dan" ["A Troop of Boy Detectives"], "Yôkai Hakase" ["A Monstrous Doctor"], and so on. In 1954, a movie based on this story was produced.