Japan will closely monitor speculative and other developments in the foreign exchange market “with a high sense of urgency” after the U.S. dollar topped the 150 yen line, a senior Finance Ministry official said Friday. “We are aware that there are slightly one-sided or rapid moves” in the market, Japan’s top currency diplomat Atsushi Mimura told reporters, after the dollar exceeded the key level in New York on Thursday for the first time since early August. The dollar’s advance came after the release of stronger-than-expected U.S. retail sales figures, while it has been bought against the yen …