This book, at the nexus of migration and urban studies, sheds new light on a long-neglected group of transmigrants and the global city of Tokyo. Using extensive empirical material on transnational migrants from above and below, it locates and better specifies spatial diversification in Tokyo and beyond. By incorporating transnational spaces into urban diversity discourses, it extends the superdiversity debate to a socio-spatial dimension and examines the configuration and processes of diversity and diversification in global cities from a socio-spatial perspective. Unique in its theoretical focus on the spatial aspect of superdiversity, the book delivers rare empirical insights into the daily socio-spatial practices of transnational financial professionals and other transmigrants. This social geographical study reveals the complex interplay between global mobility and urban transformation. It will be of particular interest to urban and migration scholars in fields such as urban sociology, social geography, and urban anthropology, offering deep engagement with debates on urban diversity and transnational spaces.