The International Military Tribunal for the Far East (IMTFE) found Japan guilty of deliberately promoting drug abuse as a weapon to further its imperialistic aims in Asia. This study provides the historical context behind the IMTFE's findings from the annexation of Taiwan in 1895 to the end of World War II. Given the extent to which drug use permeated the politics, economy, and culture of Asia, it was inevitable that Japan's rise as an imperial power would lead to contact with, and increasing involvement in, the opium and narcotics trade. This study argues that the nature of that involvement should be understood not simply in terms of a conspiracy to drug the people of Asia into submission, but rather as indicative of the general twists and turbans of Japanese imperialism. Thus, opium and narcotics emerge not so much as a weapon of, but rather as a metaphor for, Japanese imperialism in Asia.