Despite the fact that oil imports in September this year were still based on the previous higher oil prices, the Japanese goods trade surplus increased that month
, as exports to both China and America boomed. When the lower oil prices soon lowers the oil import bill, the goods trade surplus will likely rise even faster.
And the overall current account surplus probably rose much faster as the service trade deficit have been declining and the investment income surplus have been soaring
so far this year.
All of this again illustrates that the yen is greatly undervalued