In 1877 Robert Myers and four others living on the Bonin/Ogasawara Islands became the first foreigners to be naturalized as Japanese subjects after more than two hundred years of Japan's semi-exclusion from the outside world. In the space of five years, fifty-nine other first settlers became Japanese subjects/‘naturalized foreigners’ through entry on the Household Family Registry (koseki). At a time when Japan was emerging from a feudal-like system to a modern nation state the Islands were one of Japan's first attempts, in modern times, at overseas expansion. The multinational community on these islands presented the Meiji authorities with unprecedented challenges that could only be overcome through extraordinary measures. In this study I explore the circumstances and context surrounding the unusually placed Bonin Islanders in the late nineteenth century to shed light on the processes of Japanese colonization and social control. I argue that the koseki, as an instrument of ‘bio-power’ (Foucault, 1998: 140), was indispensible in successfully legitimizing and exercising sovereign power over the Islands.