Erin Aeran Chung's welcome contribution to migration studies examines immigration and citizenship in the important case of Japan. Japan is a country that, given its low birth rates and rapidly aging population, absolutely needs immigrants, is absolutely attractive to immigrants, and absolutely does not want immigrants. This is puzzling, and scientists instinctively gravitate toward puzzles. Chung touches on this issue, but her book really focuses on a related question: Why is Japan the only country with a fourth-generation immigration problem? The “problem” is Korean residents, who are in many ways indistinguishable from ethnic Japanese but who in most cases remain foreigners, although their parents, grandparents, and often great-grandparents were born in the country.

Chung's answer is partly predictable—a word I am not using pejoratively—and partly unpredictable. In the former sense, neither the Japanese government nor its citizens wanted Koreans to naturalize. That much we would have guessed. Most Koreans ended up in Japan as a product of imperialism and war. After 1945, the Japanese government, with the support of the occupying Americans, stripped Koreans of their imperial Japanese nationality and sought to encourage their return (pp. 74–77). When most opted to stay, they remained as Koreans residents in Japan.

The story in subsequent decades becomes more complex and less predictable. Koreans remained Korean not only because naturalization was difficult but also because peak ethnic associations—Kankoku representing South Koreans and Choryỡn representing North Koreans—actively opposed naturalization. They, and above all Choryỡn, opposed naturalization and integration as a betrayal of North Korean nationality and as unthinkable in the light of Japanese treatment of Koreans during the war. What is more, Choryỡn, although Chung studiously avoids this conclusion, comes across as essentially a den of traitors, from the Japanese perspective. Shortly after the war, it issued a joint declaration with the Japanese Communist Party urging the “overthrow of the Japanese government” and calling for clashes with the police (p. 79). As Choryỡn commanded majority support among the Korean population in Japan (p. 78), this declaration was not a trivial matter. The government declared Choryỡn a terrorist organization and banned it in 1949. Although other Korean organizations—Mindan and Chongryun—were not politically extremist, they remained opposed to political, and even some forms of economic, integration. This strategy reached its crescendo in the early 1970s, when both organizations initially opposed a landmark human rights case against Hitachi, which refused to hire a Korean because he was not Japanese (p. 97), on the grounds that a change in the law would encourage assimilation. What is more, these organizations pursue a strategy of political and at times economic segregation very much against the wishes of Koreans in Japan.

One of the many revealing findings of this book is that 80% of Koreans intermarry with Japanese citizens, itself a high measure of cultural integration. The picture that emerges—one that Chung might have painted in brighter colors—is of an unholy alliance between Japanese conservatives and Korean nationalists with the aim of preventing Korean integration. The extremes do meet in the center. She convincingly shows how a seemingly simple story of Japanese ethnic preference is, in fact, a much more complex one.

As an empirical study of Japan, this book is very impressive. At times, the conclusions seem to be drawn from a relatively small number of in-depth interviews, but this sort of ethnographic research is an established and respected method of social-scientific inquiry. Where Immigration and Citizenship in Japan is less convincing is in its use of theory. The broadest claim in the book is that Koreans have gained more by lobbying as foreigners than they would have as citizens (p. 174). This central contention remains unproven: To know this, we would need to compare a large group of Korean permanent residents with a large group of Korean citizens. Since we lack the latter, any speculation about how a politically integrated Korean community might behave remains exactly that.

Chung's treatment of the comparative literature is at best cursory. A single-country case study does not need a comparative approach, but she aims at it, and that aim needs to be evaluated. Her discussion of Rogers Brubaker's culturally determined model of citizenship does not note the extensive criticism to which that model has been subjected (see Dieter Gosewinkel, “Citizenship and Nationhood: The Historical Development of the German Case, in Ferran,” in Requejo Coll and Ulrich K.Preuss, eds., European Citizenship, 1998); it also does not note that Brubaker himself has adopted a more political understanding of citizenship in recent work (“Migration, Membership, and the Modern Nation-State: Internal and External Dimensions of the Politics of Belonging,” Journal of Interdisciplinary History 41 [no. 1, 2010]: 61–78). The German case is invoked casually, and it seems chiefly with the elusive aim of finding a comparison that makes Japan's approach to immigration and citizenship appear liberal. Her claim that Germany's citizenship policy toward Aussiedler was a sort of völkisch clubbiness grossly oversimplifies the matter and is based on another book that examines Japan (p. 162; for the citation, see p. 186). The point (made again to relativize Japan's restrictive approach) that all citizenship policies are made up of a mix of descent, birth, and residence is well taken, but it was made some years ago by Marc Howard (“Comparative Citizenship: An Agenda for Cross-National Research,” in Perspectives on Politics 4 [no. 3, 2006]: 443–55).

Finally, throughout the book, the author seems unclear as to how her own conclusions relate to postnationalism. She seems to think that her book provides partial confirmation of the theory. In fact, it is—were another needed—a searing indictment of it. Japanese and Korean hostility to political citizenship has left Koreans, rather unremarkably, politically excluded, and it has not (whatever one book cover endorsement suggests) undermined the dominant Japanese self-understanding as a homogeneous nation utterly opposed to immigration.

Whereas differences of interpretation between the author and this reader remain, there can be no question that this book is a significant achievement, one that deserves a spot in university libraries, on course syllabi, and in scholars' private libraries.