This book examines Japan s Household Registration System ("koseki seido"), which despite its ubiquitous influence and historical significance, has not yet been dealt with comprehensively. By looking through the lens of the "koseki" system, the book takes both an historical as well as a contemporary approach to understanding Japanese society. In doing so, it provides insight and understanding of contemporary Japan within the historical context of population management and social control; reveals the social effects and influence of the "koseki" system throughout its history and presents new insights into citizenship, nationality and identity.