It was only a matter of time. Japan’s stock market, which has soared nearly 50 percent in the past half year, took a hard fall on Thursday. Japan’s central bank has been engaged in an aggressive push to jump-start growth by flooding the economy with cheap money and devaluing the yen. That has worked wonders for the markets. But investors, processing a rise in interest rates and weakness from China (an important trading partner), sold stocks with abandon. The Nikkei 225 index fell 7.3 percent on the trading session.