The front cover of Eiichiro Azuma’s masterful new book reproduces the sepia image of a Japanese man, feet planted on top of the world and hands reaching up to the heavens. Below the man – who on closer inspection seems to be a mannequin – is the slogan, kaigai hatten, „Overseas development“. The image comes from an exhibition called „Our New Frontiers“, which opened in Tokyo in January 1940 and attracted more than one million visitors. Coinciding with the beginning of the year-long jamboree to mark the 2.600th anniversary of the nation’s founding (as the propaganda had it), „Our New Frontiers“ celebrated – in not unproblematic ways – the multifaceted history of Japanese overseas expansionism after the 1868 Meiji revolution. This is a history whose own frontiers have generally been studied in the postwar period as coterminous with the formal empire – that is, with Japanese colonies in northeast Asia, the southwest Pacific and ultimately in wartime southeast Asia. But as Azuma convincingly demonstrates, what he calls „Japanese America“ was also central to the story of Japanese expansionism from the 1880s to the 1930s. Indeed, such was the „supple orientation“ of transpacific settler colonialism that Japanese imperialism may better be understood as „extend[ing] outside the bounds of its sovereign and military power“ (p. 263). In this sense, and in the words of the book’s subtitle, Japan constituted a „borderless empire“.

This is a ground-breaking thesis, to date the boldest expression in English of ideas that have been percolating for more than a decade in research projects in Japan and elsewhere. Masterfully researched and boldly conceived, In Search of our Frontier should begin to redefine the terms of Japanese imperialism for years to come.

The originality of Azuma’s contribution firstly lies in his extraordinary reconstructions of the Japanese in America. Almost in the mode of a biographical dictionary, In Search of our Frontier offers numerous portraits of Japanese men on the move, each of whose careers fundamentally disrupts contemporary epistemologies of „colonist“ or „migrant“ which the historiography has too long reinforced. Consider Takekawa Tōtarō (1868–1911), who emigrated to San Francisco in 1884 and stayed until 1897, encouraging Japanese settlement not only of the Californian frontier but also (especially after the rise of anti-Japanese campaigns among the state’s white population) of neighbouring Mexico. Thereafter, Takekawa used his membership of the influential Colonization Society, established in 1893 in Tokyo, to finance various projects in China, which he imagined as the grateful beneficiary of future Japanese overseas development (that slogan again). With his establishment of a Japanese-language newspaper in Shanghai (1903), his founding of a Japanese academy for reform-minded Chinese in Chongqing (1905) and his opening also of a match factory in that city, Takekawa was an early practitioner of Japanese expansionism into northeast Asia. Meanwhile, back in California, his younger brother, Minetarō, pushed for a major Japanese settlement of Pacific-coast Mexico, especially after that country’s 1910 revolution. To this end, he and his fellow expansionists were supported by capital both from the metropole and from major sugar interests in colonial Taiwan. California, China, Mexico, Taiwan: oversimplifications notwithstanding, my summary of the Takekawa brothers hopefully gives a sense of the type of protagonist who stalks the pages of In Search of our Frontier, and of Azuma’s meticulous archival work in tracing the lives of such transpacific migrants and „remigrants“. For specialists, the book’s extended footnotes are also a treasure trove of further information.

Second, by reconstructing the experiences of Japanese lives in America, Azuma also elucidates a Japanese idea of America. „Japanese settler colonialism,“ he concludes, „continuously held the US historical precedent of agrarian settlement and frontier colonization as a principal point of reference“ (p. 262). Thus, even as Japanese settlers in the United States became victims of anti-Japanese racism in the first decades of the twentieth century, they continued to frame an imagination of subsequent colonial settlement according to a white supremacist rhetoric of the „frontier“ in, say, Manchuria, or of Puritan-style „pioneers“ in, say, Taiwan. Azuma thereby articulates a grand historical irony: even as white racism foreclosed Japanese settler ambitions in California, it motivated Japanese expansionism into Latin America or Asia. Satō Torajirō (1864–1928) had a similar story: after studying in the US, his experience of racism in British Australia led him later to promote Japanese settler colonialism in Korea. In other cases, „remigrants“ not only transplanted know-how and machinery from the Californian frontier or from the pineapple canneries of Hawai‘i to the formal colonies but also, in some cases, US racist hierarchies. This time round, however, the Japanese fulfilled the role of the white frontiersman bringing cultivation and civilization to the „natives“ (dojin).

As should by now be clear, a third significance of Azuma’s Japanese America framework is that his „America“ encompasses North, Central and South, rather than being confined, as in so many studies, to the United States. For a period, Mexico loomed especially large in the imaginations of intellectuals in Tokyo and boosters in the US, as the Takekawa example partly shows. After the Great Kantō earthquake (1923) and US anti-Japanese immigration legislation (1924), Brazil then became the key locus of state-sponsored expansionist dreams.

And thus to Azuma’s key argument, running through each of his eight chapters, about the „cross-fertilization of colonial projects between imperial Japan and Japanese America“ (p. 10). Here is one articulation of that argument: „The stories of experienced California farmers in Manchuria, and those of Hawai‘i-based investors and resettlers in Taiwan and Saipan, all shed light on the hitherto unknown translocal colonial migration circuits and the homeland-immigrant nexus that rendered the formal empire and its extraterritorial immigrant society indispensable partners in the common goal of overseas Japanese development“ (p. 213). As elsewhere in the book, this is a densely argued sentence. The most important historiographical intervention, in my view, is the idea of a „partnership“ between Japanese settlers within and without the formal borders of the Japanese empire – between men, and to a lesser numerical extent women, who were previously classified either as „colonists“ (shokumin) or „migrants“ (imin) according to their migration’s endpoint. Azuma’s all-encompassing notion of „settlers“, whether in Brazil or Manchuria, Hawai‘i or Saipan, forces a major rethinking of both the actors and the spaces of Japanese imperialism. As he points out, this is both an unknown story and one which has been neglected in the vast majority of previous scholarship – partly due to historians inadequately incorporating Pacific sites of Japanese history into scholarship overly centred on the empire’s formal borders.

And yet, I wonder how much the key notion of a „borderless empire“ advances our analysis of Japanese transpacific history. True, its usefulness derives from its historiographical shock-value, in reminding historians that Japanese imperial practices and imaginations did not end at the borders of the formal empire; and, moreover, that the genesis of settler expansionism was often found in Japanese America. But in other parts of the text, Azuma’s language of „translocal“ or „transborder“ circuits of people and knowledge seems more useful to me in describing both how the book’s protagonists were conscious of geopolitical and racial borders in the Asia-Pacific world, and how they strove – and often failed – to accommodate such borders in their daily lives. Meanwhile, Azuma has provided many examples of how Japanese settlers imagined their relationship to the „natives“, whether in Taiwan or Mexico, the United States or Manchuria. But the challenge remains, where possible using indigenous languages such as Hawaiian, to test the extent to which Japanese-„native“ relationships differed across the borders of sovereign and military power – and thus the extent to which „borders“ may remain a useful analytical category.

Building on Azuma’s lead, there is more work to be done on refining our analytical terms and perhaps eventually moving beyond his „borderless“ framework for Japanese imperialism. That said, scholars will repeatedly return to In Search of Our Frontier as we seek to develop new ways of understanding one of the modern world’s most important empires.