The energy sector in Japan presents certain particularities that have contributed to the country's economic development. The paper examines these specificities in relation with the Japanese energy demand. The article also aims to describe the evolution of the energy branch in Japan from the end of the Second World War until the 2011 Fukushima Daiichi nuclear disaster with suggestions for balancing the Japanese energy mix in the future. Japan has deficiencies in reserves of fossil fuel, except coal, and relies heavily on imports of crude oil, natural gas, and other energy resources. This is the main reason why Japan developed a strong energy research and development program supported by the government in order to boost the country's energy efficiency. The shortage of natural resources also determined nuclear energy becoming a national strategic priority in Japan, even though there had been ongoing concerns about the nuclear reactors' capacity to operate efficiently when confronted with Japan's oft-repeated seismic activity. While Japan had arrived to rely on nuclear power to accomplish more than one fourth of the country's necessities of electricity, after the 2011 Fukushima Daiichi nuclear disaster all nuclear reactors have been gradually shut down due to security reasons. With many reservations in August 2015, the Sendai Nuclear Power Plant was brought back online being in 2016 the only nuclear power plant functioning in Japan. However, Japan finds nowadays itself in the position to redefine its future energy structure, promote renewable sources of energy and re-evaluate from technological and economical points of view the status of all nuclear plants.