During Japan's heady bubble era in the late 80's and early 90's, it seemed that every Japanese person I met proclaimed that golf was their favorite hobby. Then the bubble crashed and not a few Japanese companies went belly up—many because they had speculated in real estate, oftentimes investing in the plethora of new and exclusive golf courses being built around the country (many of those went belly up too). But when the cash dried up, it seemed like a lot of casual players lost interest; it was expensive to play and the courses were often crowded. Younger Japanese started spending their money elsewhere.
But in recent years, there's been a change. Golf has become cool again amongst some of Japan's most important trendsetters, otherwise known as OLs ("office ladies").
I'm not quite sure why, but my intuition tells me that it has something to do with the prominence (and often dominance) of Japanese and Korean women in many of the world's most important tournaments. As of September 1, 2008, 24 of the world's 50 top-ranked women's golfers are Japanese or Korean (nine Japanese, 15 Koreans). The media has picked up on this, and the increased awareness amongst women (and other young people) has probably led a lot of them to give golf a try.
In any case, the new popularity has resulted in a bonanza for companies that export golf balls to Japan.
According to the Tokyo Customs authorities, 2007 was a record year for golf ball imports, both in terms of volume and value (up 17.6% and 12% respectively, vs. 2006).
It will be interesting to see if the boom lasts. Golf remains a fairly pricey pastime, and if women start investing in expensive gear, club memberships and regular greens, that's all the less they'll have to spend on luxury fashion brands, dining out, and travel.

