"Yet, if the central bank took its domestic job more seriously, a lot of the currency problem would melt away.
The Bank of Japan has long been experimenting with policy instruments that are well beyond what central banks in other big economies have tried. However, despite being innovative in scope, these policies have been largely conservative in scale, doing little to end Japan’s deflation.
A more aggressive quantitative easing programme, targeting 10-year government bonds instead of shorter maturities, would contribute more decisively to ease the pressure on the exchange rate. More importantly, it would also stimulate the largely stagnant domestic economy. This is the real question that Japan should try to address."

http://www.ft.com/intl/cms/s/0/79813760-03dc-11e1-98bc-00144feabdc0.html