Japan's May exports fell 2.7 percent from a year earlier, tumbling for the first time in 15 months, data on Wednesday showed.
The fall compared with a 5.1 percent jump the previous month and analyst expectations in a Reuters poll for a 1.2 percent decline.
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Imports meanwhile fell 3.6 percent on-year, compared with expectations for a 1.7 percent rise.
This brought Japan's trade balance to a deficit of 909 billion yen ($8.9 billion) in May.
"If we look at the imports of consumer goods and isolate that from resource prices, of course there might have been a connection there," said Europacifica Consulting CEO Naomi Fink, talking about the reasons behind the decline in imports.
"We did, after all, have a decline in demand after front loaded demands before the tax hike so that's only normal," she added.
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Japanese consumers ramped up spending in the first quarter of this year -- ahead of a rise in the country's consumption tax that took effect in April.
Japan's markets showed little immediate reaction to the trade data, with the benchmark Nikkei stock index opening slightly firmer while the yen was little changed around 102.2 per dollar.
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