Due to Japan brews and produces beer, the consumption of beer in Japan is mostly domestic beers. Japan was number 5 of the consumption of beer per country in 2018, but number 50 when the consumption is per capita, 40.2 liters per person per year.
Anyway, you can buy or order imported beers in Japan, mostly in big cities too. The major imported beers are Budweiser(the American one), Heineken, Corona, and Guinness. However, mostly are bottled ones except Guinness which you can enjoy draft one.
Then, due to Czech number one brand, Pilsner Urquell was bought by Japanese Asahi Beer, draft Pilsner Urquell is possible to drink too but the price is extremely expensive than you drink in Prague.
If you go to supermarket, you can find more brands, mostly German or Belgian beers. On the other hand, there are Asian and American brands which are hardly to get in Europe. Anyway, do not drink too much!