Japan's current account surplus doubled in fiscal 2015 to 17.9 trillion yen, or around 165 billion dollars from the previous year, largely thanks to lower crude oil prices.

    The current account is the broadest measure of a country's trade and investment with the rest of the world. Japan's Finance Ministry says the surplus grew by about 85 billion dollars year-on-year, approaching a level last seen in fiscal 2010, the year of Japan's worst postwar disaster, according to Japan's (NHK WOLRD) radio. 

    The trade account - exports minus imports - was back in the black for the first time in five years, posting a surplus of about 5.8 billion dollars in fiscal 2015. This can be largely attributed to a decline in the value of imports, due to lower crude oil prices. 

    The primary income account, which gauges how much Japan earns from its overseas investments, also posted a surplus of about 190 billion dollars. That's the largest since fiscal 1985, when comparable data became available. The figure reflects growing dividends from overseas affiliates of Japanese companies. 

    The service account, on the other hand, registered a deficit of about 11.1 billion dollars. But it shrunk from the year before, thanks to a record number of foreign tourists. In March, the current account stood at about 27.4 billion dollars, posting in the black for the 21st consecutive month, helped by a widening trade surplus.