Tokyo stocks fell for the first time in three trading days Monday, with the Nikkei Stock Average plunging 340.32 points, or 2.71%, to end the day at 12,220.63.It was the steepest slide in the benchmark index since Aug. 5, 2011, when it plunged 359.30 points, according to (Nikkei.com) website.The dollar and the euro weakened against the yen amid uncertainty over the euro zone’s bailout plan for Cyprus. Worsening investor sentiment prompted selling of a broad range of issues, with selling of stock index futures and some high-price stocks weighing on the Nikkei average.The trading value on the first section of the Tokyo Stock Exchange totaled about 2.16 trillion yen on a preliminary basis.