The Nikkei stock index fell for the seventh straight day Wednesday, hit by a stronger yen after a Bank of Japan policymaker signaled willingness to raise interest rates further depending on economic developments. The equities market was also pressured after U.S. Democratic Vice President Kamala Harris, advocating a higher corporate tax, appeared to have a slight advantage over Republican candidate Donald Trump following the U.S. presidential debate, brokers said. The 225-issue Nikkei Stock Average ended down 539.39 points, or 1.49 percent, from Tuesday at 35,619.77. The broader Topix index fin…