But the Japanese have to play by the same rules as everyone else. Oh, sure, you can get a kind of submission from a conquered people by scaring the shit out of them, but it doesn’t work very well to hold a knife to someone’s throat and say, "I want you to believe that this piece of paper is worth ten pounds sterling." They might say that they believe it, but they won’t really believe it. They won’t act as if they believe it. And if they don’t act that way, then there is no currency, workers don’t get paid (you can enslave them, but you still have to pay the slavedrivers), the economy doesn’t work, you can’t extract the natural resources that prompted you to conquer the country in the first place. Basically, if you’re going to run an economy you have to have a currency. When someone walks into a bank with one of your notes you have to be able to give them gold in exchange for it.