Hiromichi Tsuyukubo ran the best-performing fund in Japan at Mitsubishi UFJ Asset Management Co., an arm of the nation's biggest lender. Then, after six years, he decided to join a hedge fund.

"Back at my old job, I couldn't protect my clients' money with all the investment restrictions," said Tsuyukubo, 48, who joined Tokyo-based Myojo Asset Management Japan Co. last year. "With the new job, I could start from scratch as to how I will manage the fund. That's a big reward."

The number of hedge funds in Japan has in five years tripled to 270. Assets have more than doubled, to $36 billion, in the same period. Investors are seeking returns better than Japanese stocks, which have underperformed global shares over the past three years.