Research | Masako Hattori, PhD

1. The Age of Youth: American Society and the Two World Wars (Cambridge University Press, 2025)

By weaving together the history of U.S. foreign relations, U.S. political history, and the history of youth and education, this book demonstrates how national security concerns shaped and reshaped American ideas about youth, their roles in national security, and their access to education in the first half of the twentieth century. The title, "The Age of Youth," therefore, has two meanings: throughout this period, American adults paid close attention to young people due to recurring national emergencies (both real and perceived), making this period an "age of youth," and as a result, the definition of youth (particularly the ages considered "youth") was defined and redefined. By exploring the evolving link between youth, national security, and education across peacetime and wartime, the book challenges the widely held assumption in U.S. historiography that war and military issues had little to do with American society during the first half of the twentieth century except when the country was officially engaged in the world wars (and so the subtitle is "American society AND the world wars," not "IN"). Based on bilingual archival research in English and Japanese, I also reveal the bidirectional nature of this dynamic: national security concerns influenced educational policies in the United States from World War I to World War II, which in turn shaped how U.S. authorities in Japan in the years after World War II treated young Japanese people.

Click here for more about this book (the paperback edition will be released in 2026).

I spoke about my book with the academic blog The Way of Improvement Leads Home. Find the interview here.

(Update: July 8, 2025) It has recently been discovered that in some e-book versions of my book, book titles, journal titles, and newspaper titles that should appear in italics in the footnotes do not. This technical error is currently being addressed by the press. The PDF version should look fine.

2. Layers of Imperialism: The U.S. Military and Urban Tourism in Twentieth-Century Japan

You typically look at Okinawa when attempting to understand how the U.S. military has influenced Japanese society. Or maybe Yokosuka. In fact, the 75-year presence of the U.S. military in Japan has influenced local cultures not only in these and other locations that host military bases, but also in places that appear to have little to do with military affairs today. Moreover, the U.S. military has not been the only military or external force shaping local cultures in Japan. Up until World War II, the Japanese military shaped cultures, as did European and American commercial expansion in East Asia since the nineteenth century. Using Kobe as a case study, "Layers of Imperialism" situates the presence of the U.S. military in the Asia-Pacific region after World War II within a broader history involving Japan, the United States, and European powers and dating back to the late nineteenth century. Today, Kobe is rarely identified with the U.S. or Japanese militaries and instead is widely recognized as a cosmopolitan tourist destination. Nonetheless, a detailed examination of the city's history illuminates the city's close connection with war and military issues in the twentieth century. How, then, did Kobe establish itself as a peaceful, cosmopolitan city? Building on multiple fields of historical scholarship, such as race and gender in colonial settings, immigration and labor, and public memory, as well as growing cultural studies literature that investigates the linkages between military bases and tourism, this project illuminates the cultural, racial, and gender dynamics that drove the emergence of a tourist city that built on, but erased, a multifaceted imperial past. By doing so, it redirects historical scholarship on the U.S. military's connection with host societies, which has focused disproportionately on locations with military bases.