Since 2011, renewable energy has steadily expanded in Japan, accounting for 20% of the country’s total electricity generation (excluding large-scale hydropower) as of 2023. In light of Japan’s energy mix goals and commitments under the Paris Agreement, further adoption of renewable energy is both expected and necessary. As Japan accelerates its transition toward a decarbonized society, its energy systems are entering a new phase. With this mega trend in mind, this publication provides comprehensive coverage of developments across all forms of "new energy"—including various renewable power sources, energy management, hydrogen, energy storage, and thermal energy. Achieving a sustainable society from both environmental and industrial perspectives will require a balanced approach to energy systems, emphasizing the “3E+S” principles: Energy security (stable supply), Economic efficiency, Environmental compatibility, and Safety. By promoting the adoption of new energy technologies, this publication supports the development of innovative energy systems and serves as a resource for the entire ecosystem of the energy industry, including government bodies, businesses, and research institutions.