Tokyo stocks opened nearly flat Tuesday on thin trading after U.S. and British financial markets were closed overnight for national holidays. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 13.40 points, or 0.03 percent, from Monday to 38,886.62. The broader Topix index was up 0.09 point at 2,766.45. On the top-tier Prime Market, decliners were led by metal product, and pulp and paper issues, while electric power and gas, and oil and coal product issues led gainers. At 9 a.m., the U.S. dollar fetched 156.82-85 yen compared with 156.90-93 yen in Tokyo at 5 p.m. Monda…