Tokyo, Aug. 15 (BridgeNews) - Japanese shares ended the morning session lower in reaction to Tuesday's sharp gains triggered by the Bank of Japan's unexpected decision to ease monetary policy. Investors were cautious about pushing the market too high amid lingering concerns over the unwinding of crossheld shares, brokers said. The Nikkei 225 Stock Average fell 177.99 points, or 1.5%, to 11,739.96.