This dissertation examines the relationship between Japanese detective fiction and the territories under Japanese colonial rule, areas such as the South Seas, Korea, and Manchuria known collectively as the "outer territories" (gaichi), during the early 1930s. It analyzes the works of three detective fiction writers: Yumeno Kyusaku (1898-1936), Oguri Mushitaro (1901-1946), and Kim Nae-Seong (1909-1957). The colonial settings of their works have various functions. In Kyusaku's work, these are largely domesticated through the use of tropes and recognizable images. Through these tropes and images, he depicts colonial space as a site where community is lost, but can be recuperated through the violence of suicide. On the other hand, Oguri's work depicts colonial space as completely unfamiliar, not only through the descriptions of a contaminating, foul landscape, but also by utilizing the conventions of a locked room mystery. In doing so, Oguri challenges the scientific conceit of this subgenre of detective fiction, a conceit also present in the story's inclusion of eugenics discourses. Kim Nae-Seong's detective fiction differs from those of Oguri and Kyusaku by eliding the otherness of the colonial landscape. That is, his works portray Seoul and Pyongyang as extensions of the metropole, generic urban sites of mystery. Taken together, this set of texts illuminates the intersection of a popular genre with colonial discourses during the fraught period of the 1930s.