Nikkei falls and yen surges as Japan holds interest rates
Japanese shares fell and the yen surged after the Bank of Japan decided against any extra monetary easing.
The Bank of Japan kept interest rates unchanged despite coming under pressure to take further action.
It had introduced negative rates in January but this failed to provide a much needed boost for the economy.
The Nikkei 225 finished 3.6% lower at 16,666.05. New economic data also showed a slip back into deflation while industrial production expanded.
Japan has for years been trying to boost its economy and end a period of stifling deflation.
One way to try to achieve this is by monetary policy, which is one of Prime Minister Shinzo Abe's three key "Abenomics" policies to turn around the economy.
But even negative rates - meaning commercial banks will be charged if they deposit money with the central bank - have not trickled down to get banks to lend more and companies and people to invest or spend more.
Inflation is still far off the 2% target.
The Bank of Japan's decision to hold rates also sent the yen currency soaring, which is likely to have a negative affect on the crucial export sector.
The yen rose nearly 2% against the dollar, with one dollar worth 109.33 yen.
"This shows that too much expectation of further easing had been priced in and the BOJ has surprised the market by taking no action," said market analyst Margaret Yang of CMC Markets.
"It is probable that the central bank is temporarily running out of tools to stimulate the economy, or they need more time to observe and assess the impact of negative interest rates."
The three arrows of "Abenomics":
- The monetary arrow: expansion of the money supply to combat deflation
- The fiscal arrow: increased government spending to stimulate demand in the economy
- The structural arrow: structural reforms to make the economy more productive and competitive
Markets elsewhere in Asia were also affected by the surprise from Tokyo.
In China, the mainland's Shanghai Composite index closed down 0.3% at 2,946.20, while in Hong Kong the Hang Seng edged up 0.1% to 21,388.03.
In South Korea, the benchmark Kospi index lost 0.7% to close at 2,000.93.
Earlier on Thursday, Korean tech giant Samsung reported a 10.6% rise in net profit for the first quarter, driven by strong sales of its Galaxy S7 smartphones. The results matched the company's guidance that was issued two weeks ago.
Samsung's shares closed down 2.7%, reversing three days of gains.
In Australia, Sydney's ASX/200 index closed up 0.7% at 5,225.40.