Japan, a frustration for the world's sharpest hedge fund minds for more than a decade, is proving one of the industry's biggest winners this year. Big names from New York to London have made billions betting that "Abenomics" - the monetary stimulus programme launched under Prime Minister Shinzo Abe - would send the yen sliding and stocks surging. And funds dedicated to Japanese markets have performed better than others - their percentage return on investments is more than triple the overall hedge fund average this year, according to data from Hedge Fund Research. Now there are tentative signs that funds are preparing for a more structural shift back into Japan, convinced that if its economy is finally on the road to recovery, they can no longer ignore the world's second-largest financial market. "Japan has been a relatively ignored and underinvested market for a long time," said Nick Linnane, a hedge fund manager at Cube Capital who previously worked in Japan and has investments in several Japanese banks. "The consensus now is you need to do your research." Some funds are dusting off their old contact books to recruit stock pickers who can grapple with Japan's complex corporate make-up, while more Japan-dedicated funds are opening than closing for the first time since 2007, data from industry tracker Eurekahedge shows. This reflects the view held by a growing number of funds that there is money to be made in Japan beyond riding the big moves that have followed in the wake of the monetary stimulus. So far, hedge fund flows into the country sparked by the monetary easing have held up despite a rocky few months as the rally in the Nikkei and the slide in the yen ran out of steam. "They believe that there is a significant trading opportunity that will last years, not just six months. What has been remarkable has been the interest from US managers," said Michele Gesualdi at Kairos Partners, which chooses hedge funds to invest in. According to an Eurekahedge survey, the proportion of their money invested in Japan by funds which can trade globally was 9 per cent in September, up from 5.4 per cent a year earlier. Meanwhile, funds dedicated to Japan - which cannot dip in and out of the country - are winning back investors, albeit slowly. After recording net outflows worth US$4 billion between June last year and May, investors have added US$340 million to these funds in the past four months, and total assets have risen to US$15 billion from US$14.4 billion at the start of the year, Eurekahedge data shows. However, talk of a structural shift back into Japan by hedge funds is greeted with scepticism by some managers. The number of Japan-dedicated funds, whether based in Tokyo or in the larger hedge fund centres of Hong Kong and London, is a fraction of what it was 10 years ago. Between 2006 and last year, such funds made money in only two years and lost an average of 2 per cent a year, according to Hedge Fund Research. Previous predictions that the country's economy was turning a corner have also unravelled amid stubborn deflation and weak consumer spending, sending foreign investors towards the exit.