This open access book presents the latest Japanese research for the projection of climate change impacts and the evaluation of adaptation policies, with a particular focus on the S-18 Project—a nationwide, interdisciplinary research initiative involving experts from various fields. Readers can get a comprehensive view of the latest knowledge and strategies to combat climate change impacts in Japan. The topics span the research framework and future scenarios for climatic and socio-economic changes, and impacts and adaptation measures in major sectors at both national and local levels. Target sectors include agriculture, forestry and fisheries, natural ecosystems, natural disasters and coastal zones, water resources, urban infrastructure, and transportation, quality of life and human health, and economic analysis of the impacts. The book features high-resolution spatial distribution of impacts, changes in vulnerability with localities, effects of mitigation and adaptation measures, and implications of climate change policies on society. As the world experiences increased extreme weather events, this comprehensive book is a timely reference for similar studies in other countries through the presentation of research results and lessons obtained in Japan. Researchers, policymakers, and academics in environmental science, climate policy, and related fields will find this book invaluable for understanding and addressing the multifaceted challenges of climate change adaptation and mitigation. Some chapters were written originally in Japanese. The English translation was facilitated by artificial intelligence. The authors later revised the content for accuracy.