This book explores the issues of education, the use of languages and the formation of self-identification of the Japanese and Korean diasporas of Sakhalin, over a hundred years period: from the time they moved to the island, until their “return” to historical homelands in Japan or South Korea. During this time, their language environment and language of education changed 4 times and Japanese and Korean of Sakhalin continued to be a linguistic and ethnic minority. This book is of interest to researchers, students, NGO supporters and education policy makers.