Energy efficiency has become one of the most important aspects in the global energy outlook today. The depletion of fossil fuels as energy resources and global warming make it imperative for us to consider energy efficiency policies and measures as an important priority for policy-makers and every responsible global citizen.Japan has been a leading country in the area of energy efficiency. Since the 1970s when the oil crisis hit, Japan, which depends almost wholly on imported energy supplies from abroad, has been conducting various efforts on energy conservation and diversification of energy sources. As a result, Japan has achieved the lowest primary energy consumption per GDP in the world. Asian countries should learn from Japan’s success in this area, especially since their economic growth is predicted to be one of the primary drivers for growth in global energy demand.The chapters in this book are based on presentations on Japan’s energy efficiency and conservation at ISEAS Energy Forums.