This book offers a complex and problem-based analysis of the past, present, and future of smart cities in Japan’s energy transition. With 92% of Japanese living in urban areas and a goal of achieving net zero greenhouse gas emissions by 2050, Japan’s energy future will depend largely on how its cities can become smarter, greener, and more resilient. To reach these ambitions, a collective effort is required, with actions coming from Tokyo to Kumamoto, from Yokohama to Sapporo, and throughout dozens of Japanese smaller and bigger urban structures. The book addresses the key issues that have emerged or may emerge in various Japanese cities that are pursuing smart energy initiatives. The authors examine several issues including international cooperation, heating decarbonisation, foreign direct investments, city planning, housing policies, or technology-related risks in the context of Japan’s energy transition.