As of 9:15 a.m., the 225-issue Nikkei Stock Average climbed 204.45 points, or 0.89 percent, from Friday to 23,181.58.
The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, advanced 21.12 points, or 1.34 percent, at 1,600.45.
Iron and steel, securities house and metal product-oriented issues comprised those that gained the most in the opening minutes after the morning bell.
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