Since mid-November, the yen has weakened substantially against the dollar, the euro and other currencies.

The rapid decline was fueled by aggressive policy announcements by Shinzo Abe, before and after he became the prime minister in December, calling for more fiscal stimulus and for bold monetary easing, including a new 2 percent inflation target.

Other than an initial ¥10.3 trillion stimulus package, concrete actions have been missing so far. The yen's decline is rather reflecting the expectations of capital market players in Japan and more so abroad. Dubbed "Abenomics," the new economic policies have been outlined by the government in a very consistent and convincing way and thus moved the markets.