This paper examines the social consciousness of Hirabayashi Hatsunosuke's mystery novels. The pre-eminent literary critic of Japanese proletarian literature in its early days, Hirabayashi became disillusioned with the movement after the Great Kantō Earthquake and gravitated instead toward popular literature, particularly Japan's nascent mystery genre. His third mystery novel, Giseisha (“Victim"), tells the story of a low-ranking office worker who is arrested on a false murder charge and languishes in detention with little hope for release. With its unresolved ending and skeptical view of the criminal justice system, Giseisha is said to be influenced by Edogawa Ranpo's Ichimai no Kippu (“One Ticket"), a work which takes its basic concept from Arthur Conan Doyle's The Problem of Thor Bridge but adds a surprise ending which leaves the story's entire resolution in doubt. However, Giseisha also shows the influence of criticisms of the mystery genre by proletarian writers such as Maedakō Hiroichirō and Makimoto Kusurō, who argued that mysteries glorify a legal system which is profoundly biased against the proletariat and maintains the hegemony of the ruling class over the subordinate classes. Maedakō looked to Anatole France's humorous short story Putois and its satirical view of crime as a model for a more socially conscious type of mystery. In the same way, Hirabayashi looked to Anatole France's L'Affaire Crainquebille, a satire of the infamous Dreyfus Affair, as inspiration while writing Giseisha, not only referring to Crainquebille by name but also basing part of Giseisha‘s story on it.