Nikkei opened 0.36 percent higher in early Tokyo trading Monday on the weak yen. At 9:15 a.m., the 225-issue Nikkei Stock Average was up 34.20 points, or 0.36 percent, at 9,480.21. The broader Topix index of all First Section issues on the Tokyo Stock Exchange was up 2.38 points, or 0.30 percent, at 783. 84.