This book consists of the articles from the special issue of Hot Spots in the Climate System in the "Journal of Oceanography," Vol. 71 No. 5, 2015, comprising 9 chapters that cover a wide spectrum of topics. This spinoff book is a collection of papers on the scientific outcomes of a nationwide 5-year project, known internationally as the Hot-Spot Project. The academic achievement of the project has gained international recognition, making substantial contribution to unveiling the climatic role of warm western boundary ocean currents, including the Kuroshio, and associated oceanic fronts...