The yen's steep decline has burnished the outlook for Japanese stocks, prompting analysts to raise profit forecasts for currency-sensitive exporters and foreign investors to plough $17 billion into the market, the biggest monthly inflow since 2010.

With 60 percent of Japan's listed companies focused on exports, firms ranging from camera maker Nikon Corp (7731.T) to air-conditioner group Daikin Industries Ltd (6367.T) are basking in the prospect of a one-off currency boost and the chance to price their goods more competitively.

The yen has fallen about 11 percent against the dollar to around 89 yen since mid-November, reflecting new Prime Minister Shinzo Abe's push for aggressive policy action to weaken the local currency and revitalize the economy. Investors will be looking for signs that the yen's decline is bolstering profits when the quarterly earnings season kicks into gear next week.