The Federation of Electric Power Companies of Japan has an informative brochure on Japan’s current and future energy plans (pdf). It provides stats on the 10 companies that service Japan, the country’s long-term supply and demand outlook, lifecycle CO2 emissions, and the hourly supply and demand electricity curve. A few images from the pdf are pasted below.
This is just some of it. There are tables on all of the power plants by fuel type, maps of the locations of power plants and transmission grid, details on their nuclear fuel cycle and much more. It’s an excellent short and sweet piece on the country worth checking out.