As of 9:15 a.m. local time, the 225-issue Nikkei Stock Average gained 115.19 points, or 0.50 percent, from Monday to 23,320.05.
The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, added 12.21 points, or 0.72 percent, at 1,709.70.
Precision instrument, service and securities house-linked issues comprised those that gained the most in the opening minutes after the morning bell.
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