Major electric power companies Japan 2023, by total assets

As of March 2023, Tokyo Electric Power Company topped the ranking of electric power companies in Japan, with total assets worth around 13.56 trillion Japanese yen. The electric utility company, also known as TEPCO, was founded in 1951 and mainly supplies the Kanto region, including the Tokyo area.

 Tokyo Electric Power Company Holdings, Inc. 

TEPCO is known for the nuclear accident at its Fukushima Daiichi Nuclear Power Plant in Fukushima Prefecture, which was caused by the Tohoku earthquake and the following tsunami in 2011. Even though most Japanese people disapproved of how TEPCO handled the disaster, the Japanese government supported the company financially to ensure the electric power supply for Tokyo. In recent years, the company started to generate electricity using nuclear reactors again. Furthermore, it is expanding its renewable energy segment, including hydropower, thermal power, and wind farms.

 Electricity market in Japan 

The Japanese electricity market was dominated by ten regional electric companies. Competition remained limited since retailers of low voltage electricity mainly sell their electricity locally to homes and small shops. The nuclear disaster in 2011 affected the electricity market insomuch as natural gas and coal replaced nuclear energy as sources with the largest share of the electricity production. Since Japan depends on imports for fossil fuels, this caused the decline of the self-sufficiency rate of primary energy, and an increase in electricity rates for homes. The current energy policy therefore aims to diversify the energy mix, including renewable and nuclear energy. In recent years, the share of renewable energy in electricity production increased to over 20 percent.