Japan doesn’t have enough electricity. After Fukushima, they lost most of their nuclear. The country is densely populated, and the parts that aren’t populated are covered in forested mountains, which all makes building the required amount of renewables very difficult. So today and in the future, Japan runs on coal and natural gas. So they make cars that run on hydrogen (which is more efficient to create out of their imported natural gas than burning the gas for electricity) and then sell those abroad greenwashed as “but you can produce hydrogen from green electricity!”
First of all EVs do not need that much power. We are talking something like 25% more electricity production for a country like Japan. Then Japan has rather a lot of onshore and even more offshore wind potential. Mountains are a problem, but hardly something which can not be overcome. Solar can easily be installed on roofs and mountains are even less of a problem.
Also really important to say it. Combustion engines in cars are massivly inefficent. So an EV is still better for the climate, even if run with coal electricity. The other factor is that Japans population is falling. So they will need less power over the long term.
