Today, the Bank of Japan is at the top of the whiner list of strong currency complainers, despite the obvious mathematics.

Bank of Japan Governor Haruhiko Kuroda warns Current Yen Strength Risks Harming Japan Recovery".

Speaking to reporters in Frankfurt Monday, Kuroda also reiterated that BOJ policy makers won't hesitate to expand monetary stimulus in order to achieve their 2 percent inflation target. The central bank's board left settings unchanged at a meeting Thursday, spurring a nearly 5 percent, two-day surge in the yen against the dollar.

"There is a risk that the yen's current appreciation brings an unwelcome impact on the economy," Kuroda said on the sidelines of an annual gathering of finance chiefs from members of the Asian Development Bank, which he used to lead. "We will be closely monitoring the impact of financial markets on the real economy and prices."