As of 9:15 a.m., the 225-issue Nikkei Stock Average dropped 203.42 points, or 0.96 percent, from Thursday to 20,947.72.
The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, lost 11.47 points, or 0.74 percent, at 1,529.11.
Oil and coal product, marine transportation and mining-linked issues comprised those that declined the most in the opening minutes after the morning bell.
Latest comments