It would disagree that JPY always has a negative correlation to high yield currrencies. On any day it can depend upon data releases. It can depend on insitutional strategy which doesn't buy or sell a particular currency pair. They buy and sell individual currencies, and those positions move the other currency pairs. For example, if the chart for +EUR-JPY wasn't favourable to a profitable trade, what other currency pairs would you trade in order to 'buy' EUR' and 'sell' JPY? In other words the correlation is not always obvious. Listen A successful intrabank trader gives the answer.