TOKYO, Nov 25 (Reuters) - The Nikkei climbed 1.5 percent on Monday to within sight of a 5-1/2-year peak reached in May, propelled by exporters with the yen slumping versus the dollar and investors expecting the Bank of Japan to keep its stimulus drive even as the Fed tapers off. The Nikkei ended 237.41 points higher at 15,619.13, hitting a six-month high and edging closer to the 5-1/2-year high of 15,942.60 touched on May 23. Monday's rise, the seventh day of gains in 11 sessions, took the benchmark Nikkei to "overbought" territory, with its 14-day relative strength index at 72.8, above the 70 threshold which is considered overbought, signalling that the index could be ripe for a short-term pullback. Index heavyweight SoftBank Corp jumped 5.4 percent to a 13-year high, building on Friday's 2.3 percent rise after hedge fund manager Daniel Loeb revealed a $1 billion-plus stake in the mobile operator. It was the top-weighted gainer in the Nikkei and the most-traded on the main board. The weaker yen helped lift the appeal of currency-sensitive exporters, with Honda Motor Co Ltd, TDK Corp and Yokogawa Electric Corp up between 1.6 and 3.6 percent. The broader Topix index closed 0.9 percent higher at 1,259.61, with 2.53 billion shares changing hands, a tad lower than last week's daily average of 2.56 billion shares. Powered by massive fiscal and monetary stimulus, the benchmark Nikkei has risen 50 percent this year, gunning for its best yearly performance since 1972.