To elaborate, there is a tax on buying dollars, so although the 'official' price is X, the true price is X + 30% if you want to buy.
I think there might be a possibility for arbitrage eventually, since sometimes the true price is lower than the price you might get for bitcoin but the difference is so minuscule that it would take years to make an interesting profit out of it. Also, it would be a pain in the ass to wire the transfer out of the country, since for example Transferwise doesn't allow you to send money in my homeland's currency, only receive.
Personally I use Bitcoin to transfer money to my home country monthly. It's not much, around 1000-1500 euro (hopefully for just one more month), and it's to pay my credit card debt back home. It's very convenient, fast, and I get the best market price for my euros. Using Transferwise is out of the question since my homeland uses an artificial price for the dollar, and thus if I were to use them I'd lose on about 25% of my country's currency.
On your Portal point, the reason for that is that sarcasm as humor is not really a 'thing' in Japan, in general terms. Some people go as far as saying that the Japanese do not understand sarcasm, but that's an exaggeration