Just to give a bit of background, Japan is the world's third-largest importer of coal and Russia is the country's second-largest supplier. In total, Russia supplies over 10% of Japan's coal imports.
Japan prime minister Kishida says that in banning Russian coal, the country will focus on renewable energy and nuclear power to replace the lost supplies. Those aren't things that will come overnight but it highlights the long-term planning by many countries now in diversifying away from Russian energy.
Coal is obviously the easy step. Oil and gas is an entirely different ballgame but it is one that could be on the cards in the year(s) ahead.
Much like the EU, Japan also relies heavily on Russian oil and gas. For some context, the city of Hiroshima imports almost half of its gas supplies from Russia and Tokyo roughly about 10%.
It will take time to replace existing contracts and projects that are running at the moment but over time, one can expect more and more countries to continue to lessen their dependency on Russian energy.
The question then becomes, what is the long-term outlook for Russian oil and gas? I fear it is going to be a Venezuela situation but considering Putin's ideals, you never really know what might come next when his back is against the wall.