Concerns have also been rife about cases soaring in the United States and the impact any restrictions could have on the global economic recovery from the pandemic.
As of 9:15 a.m., the 225-issue Nikkei Stock Average lost 161.55 points, or 0.69 percent, from Wednesday to 23,256.96.
The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, dropped 7.90 points, or 0.49 percent, to 1,604.65.
Air transportation, iron and steel and securities house-linked issues comprised those that declined the most in the opening minutes after the morning bell.
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