This book reviews the research in various fields of oceanography on the responses of the East Japan Sea to climate change. The uniqueness of the East Japan Sea comes from the rapid and amplified response to climate change, which includes long-terms trends of physical and chemical parameters at a rate that almost doubles or even higher the global rate. This book aims to provide in an organized way the results from the previously published knowledge but also to introduce an updated view of the research recently carried out. The book is divided into several parts that comprise the physical, chemical, biological, and geological aspects of the region and fisheries. This book is made for researchers and students working on climate variability as well as for the oceanography community working on world's marginal seas. The research presented in this work will also benefit to researchers from other fields such as social scientists and environmentalists, and also policy makers.