The International Energy Agency (IEA) regularly conducts in-depth peer reviews of the energy policies of its member countries. This process supports energy policy development and encourages the exchange of international best practices and experiences. Nearly a decade after the 2011 Fukushima nuclear accident resulted in significant disruption to its energy supply, Japan has made visible progress towards realising its vision of an efficient, resilient and sustainable energy system. It has diversified its energy mix and embarked on a major reform of its electricity and natural gas markets. The gradual expansion of renewable energy sources, restart of some nuclear power plants and improvements in energy efficiency have reduced the need for imported fossil fuels and lowered greenhouse gas emissions below their 2005 level. Nevertheless, the carbon intensity of Japan’s energy supply remains one of the highest among IEA members. It will need to move quickly to make headway on the steep emissions reductions that are needed to achieve its recently announced ambition of reaching carbon neutrality by 2050. In this report, the IEA provides energy policy recommendations to help Japan smoothly manage the transformation of its energy sector.