This article explores how the Japanese translator-historian Murakami Naojirō created an understanding of the Japanese past that established seventeenth-century Japanese actors as equivalents to western European and overseas Chinese merchants. Creating a historical geography of the Southern Seas and the Pacific, Murakami celebrated Japan's expansionism, not only by stressing the seventeenth-century Japanese presence in South-east Asia, but also, more subtly, by identifying the existence of a progressive spirit in the Japanese individuals involved in it. His narrative strategy included implicit comparisons with the European age of expansion, whose protagonists in South-east Asia relied on the networks and services of both Japanese wakō (‘pirates’) and more complex actors such as the red seal merchant Yamada Nagamasa. The article is a case study for Japan's intellectual imperialism of the 1910s–1940s, which closely intertwined popular discourse and academic history.