TOKYO, Jan. 22 (Xinhua) -- Tokyo stocks opened marginally lower on Monday as a comparatively firm yen against the U.S. dollar weighed on the market amid concerns of the U.S. government shutdown.

As of 9:15 a.m., the 225-issue Nikkei Stock Average dropped 49.35 points, or 0.21 percent, from Friday to 23,758.71.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange fell 2.70 points, or 0.14 percent, at 1,887.04.

Oil and coal product, nonferrous metal and machinery-linked issues comprised those that declined the most in the opening minutes after the morning bell.