The Nikkei 225 stock index kicked off another volatile trading session on Thursday, losing more than 700 points just after the opening on the Tokyo Stock Exchange.
The drop came after two days of gains in a week marked by some record-breaking swings.
Investors are selling shares in Tokyo following an overnight drop in the Dow Jones Industrial Average in New York.
The Nikkei started the week with its biggest-ever daily drop on worries about a recession in the US and higher interest rates in Japan. That was reversed on Tuesday with a record one-day point gain.
It rose over 400 points on Wednesday after comments by the BOJ Deputy Governor Uchida Shinichi. He reassured investors that the central bank will not raise rates when markets are in such a volatile state.