You can go to dlsite, where you can buy the game with dlpoint, which can be bought by other currencies. I found this helpful help:
An easy get around is to use the dlsite points system, you pay on a website like ‘for books’ for a gift card, the only way I found to access it is through dlsite-> points-> purchase points -> purchase with card, it’s still a bit of a chore but less of a chore then using other methods and been using this to get the works, as 1 point is 1 yen, but do be aware of like transfer fees cause you’re still buying using yen, but it’s only a few $ or £ or €