Tokyo stocks opened sharply lower Tuesday, with Nikkei losing over 400 points temporarily, as selling was triggered by an overnight plunge in the U.S. market and a weaker U.S. dollar which stood at a one-month low against the yen. At 9:15 a.m., the 225-issue Nikkei Stock Average sharply plunged 385.37 points, or 2.42 percent, from Friday to 15,526.69. The broader Topix index of all First Section issues on the Tokyo Stock Exchange was down 26.18 points, or 2.02 percent, at 1, 272.30. Japanese financial markets closed Monday for a national holiday.