Japanese stocks have been on a tear, up nearly 28% this year. Billionaire investor Warren Buffett's Berkshire Hathaway added a spark in April when he traveled to Tokyo and increased his investment in five of Japan's trading houses. A press release from the company Monday detailed that Buffett has further increased his stake in the trading houses, a sign that the billionaire has become more comfortable deploying capital in Japan than in Taiwan or China. Berkshire said its stakes in trading houses Itochu, Marubeni, Mitsubishi,…
