The Nikkei index at the Tokyo Stock Exchange lost 215.88 points to 8,539.56 in the first minutes of trading. The Topix index of all first section shares fell 2.64 per cent or 19.80 points to 729.60.
The plunge in Japanese shares followed US and European stock markets sagging Wednesday as Italian debt yields soared as high as 7.4 per cent, a level seen as unsustainable for the finances of the European Union's fourth largest economy.
The surge in Italian yields came at a sensitive time for the eurozone as "the details of European Financial Stability Facility aren't nailed down yet," said Yumi Nishimura, senior market analyst at Daiwa Securities.
But investors may take a wait-and-see approach for the rest of the day, she added.
What the stars mean:
★ Poor ★ ★ Promising ★★★ Good ★★★★ Very good ★★★★★ Exceptional