Casual encounters are often the most consequential moments in the research process. It was in the summer of 2016, when I was studying at the University of Tokyo’s Historiographical Institute, that I first met with Tanaka Hiroyuki. The retired librarian had published a number of books and articles about ships, censorship, and the fascination of Edo period intellectuals with things foreign and forbidden. I had just completed my master’s thesis on the history of the Ogasawara Islands when the possibility emerged to spend a summer in Japan and attend the Association of Maritime History Conference, where our paths crossed. Ogasawara is a group of islands some 1,000 kilometers south of Tokyo, a place that tilts the entire map of modern Japan to the southeast, pushing the four main islands north and pulling an immense range of maritime space into the picture, which the country today claims for itself. I had long felt intrigued by the questions these cartographic facts impose – and by the history that structures this modern subdivision of oceanic space. Tanaka nodded and said: “I’ve got something for you.”

Shortly after our conversation, Tanaka invited me to his home, where he brought up a worn-out envelope which he said he had purchased from an antiquarian at Jimbō-chō a few years back. The envelope read in bold brush strokes: Map and Description of Munin Jima. Carefully, I opened the envelope and discerned a worm-eaten piece of yellowed paper and a booklet with thirty pages of cursive squiggles. We opened both and found in front of ourselves the map and mission log of the explorer Shimaya Ichizaemon, submitted to Shogun Tokugawa Ietsuna in the fall of 1675 (see Chapter 3, Figure 3.4). At the order of a Nagasaki shipping magnate, the captain had sailed into the vast Pacific to explore an archipelago that had just been discovered by a crew of castaways, but now the explorer examined the islands for potential habitation. The exploration ran counter to what I believed to know at that point about Japanese history: Picture Edo as a maritime capital, an Amsterdam of the East, whence merchants funded explorers to set sail to ever-farther shores and return with stories about foreign peoples, colonies claimed, and geographical data that pushed the limits of the imagined world. Was this map the antithesis to the history of a country – an entire region – that has been unduly labeled as “islanded”?

Tanaka agreed to take the fragile map to the restoration lab at the Historiographical Institute. Senior Restorer Takashima Akihiko immediately put aside the Hideyoshi manuscript he had been working on and sacrificed his weekend to delve into the recovery of this puzzling piece of paper. The repaired map with which he presented us just a few days later was confirmed to be one of only three known hand-drawn copies of a map that emerged from the Shimaya expedition. The mission log in the booklet has, to my knowledge, not been found elsewhere.

In this way, one core theme of my PhD research came to me the summer before I entered the doctoral program at Harvard University, and it has accompanied me for over a decade now. This book is an attempt at uniting the uncountable histories of people, objects, places, and ideas that have since come to my knowledge – an open-ended journey that will continue after this publication. In it, I have decided to follow the academic convention of separating the facts and sources under examination from the circumstances that have enabled my telling of this story. It shall suffice for now to share this episode and convey a sense of how every line in this book is the result of layers upon layers of thoughtful guidance, generous feedback, months and years of fieldwork, and, of course, the privilege of research funding.

I am deeply indebted to my academic advisors David L. Howell, Ian J. Miller, Kären Wigen, and David Armitage, who have accompanied this project since its inception. The intellectual freedom and institutional support I enjoyed at Harvard was simply fantastic. Thanks to a series of fieldwork grants from the Reischauer Institute, and the great support of Stacie Matsumoto and her team, I managed to spend several summers and one winter conducting fieldwork in Japan and Taiwan, starting as early as the first year of my master’s program. It was also thanks to the Reischauer Institute’s Japan Forum series that I had the opportunity to learn from too great a number of insightful visitors to list them all here. Brett Walker, who was a visiting professor at Reischauer in 2015–2016, was perhaps the most influential among them, drawing my attention to the power of environmental theory. Harvard’s campus was a truly inexhaustible chamber of treasures for my research – but it was more than that. Thanks to the friendly faces of Kuniko Yamada McVey, librarian at the Yenching Library, my program director Rosie Cortese, and my brilliant friends and colleagues among the graduate students, Harvard was my home.

I was conducting archival research in Japan with the generous support of a Doc.Mobility grant from the Swiss National Science Fund (P1SKP1_184094) in 2019–2020 when the Covid-19 pandemic struck. At that time, I was once again a guest at the Historiographical Institute, where Matsukata Fuyuko, Ono Shō, and Sugimoto Fumiko have kindly acted as faculty hosts and academic supporters at different times. I have learned so much from Gakushūin University’s Mochida Tomofumi, my resourceful instructor in paleography and the idioms of early modern Japan. I am deeply indebted to Sofia University’s Mariko Iijima, Takeshi Hamashita at the Toyo Bunko Library, and Sugiyama Rie of Kokugakuin University. In Taipei, Liu Hsiu-Feng hosted me for a summer at Taiwan’s Academia Sinica in 2017, an experience that put new archives and perspectives on the Kuroshio region on my map. And how much meaning did work on this piece gain thanks to my friends and informants in the Bonin Islands! Ludy, Yoshino, and Yulia Sforza kept me looking forward to my next visit to the Ogasawara Village Archive and they made possible so many discoveries of moss-covered inscriptions, world war remnants, and oral testimonies from their island. Likewise, Nankai Times journalist Mari Kikuchi in Hachijō helped build local connections that informed the course of this project in important ways.

My projects have received generous support and advice from numerous senior colleagues, including Andrew Gordon, Sunil Amrith, Fabian Drixler, Victor Seow, Jordan Sand, Nadin Heé, Stefan Huebner, Anthony Medrano, Paul Kreitman, William Tsutsui, Myjolynne Kim, Paul D’Arcy, and Judith Vitale. I would also like to mention my intelligent friend and fellow traveler Iijima Keitarō and his father, Osamu, who provided a true home base during my field trips. Their support was especially invaluable when the Covid-19 pandemic struck, upending, it seemed, the most vital connections for this project’s continuation. But friendship prevailed. My dear friends Reed Knappe, “Louis” Lu Yi, Anne-Sophie Pratte, Aaron van Neste, John Kanbayashi, and Shiori Hiraki, as well as William Blakemore Lyon, Fynn Holm, Kubota Masahiro, and Anton Stigö made possible uncountable conversations that all inspired different aspects of this book. It is thanks to all these crucial inputs that my PhD dissertation, on which this book is based, was honored with the inaugural Modern Japan History Association Dissertation Prize in 2024.

At Cambridge University Press, Lucy Rhymer and Rosa Martin have worked hard to guide me through the production process. Two anonymous readers have shared instrumental feedback on my manuscript, helping my dissertation come of age as a book. Having received a full funding package for my graduate studies from Harvard’s Graduate School of Arts and Sciences, I am now privileged to have access to Switzerland’s excellent research funding system. This book was made available online in Gold Open Access thanks to the support of the Swiss National Science Fund (Contribution No. 10BP12_235644 / 1). It was created entirely without the use of generative artificial intelligence.

After the completion of my PhD, I started teaching at the University of Zurich, my alma mater, where this academic journey had originally started in 2008. I have been privileged to work here most closely with Martin Dusinberre, Moe Ōmiya, Quirin Pfister, Philip Zimmermann, and Debjani Bhattacharyya from all of whom I have learned so much about writing, teaching, and the things that really matter in life. This brings me to my family. None of this would have been possible without my brother and my parents, who have always supported me in every endeavor. I am infinitely grateful to Saghar, my wife, and Kian Emanuel, my son, who is sleeping in the baby sling around my neck while I’m typing up these final lines. You are the ultimate motivation behind all of this.

This book is entirely a product of human research. No parts of it were created with the aid of generative AI.