"if you convert JPY you've earned in JPY over your lifetime, to USD, I don't think you calculate some gain/loss based on hypothetical cost basis of that JPY in USD going back forever."
Like I get that it sounds crazy, but are you aware of any rule that governs this?
If my job paid me in Japanese Yen denominated stocks since all the way back to forever, If I cash out while living in the US, I will have to include capital gain due to the exchange rate going all the way back.
