Japan's markets were trading sharply lower on Friday amid concerns over the global economy and following steep falls in Europe and the US.
The benchmark Nikkei 225 opened down more than 3.5% at 15,122.06 points.
It continued to fall in early trade to below the psychologically important level of 15,000 points, marking its lowest level since late 2014.
Shares then saw some movement upwards, but fell back again later to be down 4% at 15,087.89 points.
Overnight, benchmark indexes in London, the US and Europe posted sharp declines amid continued worries over the strength of the global economy - particularly the outlook for the world's largest economy, the US.
US Federal Reserve chair Janet Yellen's gloomy economic assessment on Wednesday was continuing to hurt investor sentiment around the world, analysts said.