SAN FRANCISCO—Before dawn on a recent Sunday, Dan Oppermann stormed into a record fair, escorting an older Japanese man who had flown from Tokyo on a mission: to buy 5,000 records in one week. "It's getting tougher," said Mr. Oppermann, 65 years old, a retired government worker. "Everyone is really hustling, trying to find new connections, new sources. "Mr. Oppermann and
a small network of fellow collectors host buying trips for Japan's record-shop owners, helping them find old LPs and CDs often considered passé in the U.S.—or simply bad—but that Japan's avid music fans have a yen for.
 

This trip's highlight: the KUSF Rock-n-Swap, a 10-hour music-lovers' convention at the University of San Francisco, where Japanese buyers and other vinyl junkies haggled with American record dealers over bargain-bin music while munching on bagels and coffee. "Our trash is their gold," says Mike Vague, 43, a music dealer who says he has 200,000 records in the climate-controlled garage of his Long Beach, Calif., home.

 

Japan has surpassed the U.S. as the biggest seller of CDs, vinyl and cassette tapes, with 25.4% of global sales, according to the Recording Industry Association of Japan. Tower Records Japan Inc.—which survived its U.S. parent's closing in 2006—opens its 87th store this month. But demand in Japan for older or niche recordings is also unusually strong. In Tokyo, Disk Union trading manager Yuji Watase said that his teams are making more trips to the U.S. than in decades.
Much of what the Japanese want goes for higher prices. Collectible artists in Japan include female pop singers like Patti Page, whose "(How Much Is) That Doggie in the Window" was a 1950s hit, and 1980s teen idol Debbie Gibson. A "Doggie" record - single goes for $5 in the U.S. and $30 in Japan, while Ms. Gibson's LPs can fetch $200 on eBay.
 

Then there are outré 1970s bands like Yes and Traffic and 1980s heavy-metal heroes Bon Jovi, Iron Maiden and Mr. Big; such albums sold for $10 to $15 at KUSF's fair. As a general yardstick, dealers say records sold in the U.S. usually fetch about three times as much in Japan. The Japanese fascination with America's musical flotsam is a legacy of Japan's music business, which for years promoted U.S. and European rock bands that never took off or were declining
in their own countries—a strategy aimed at avoiding competition with the U.S. music industry. That prompted fan cultures to sprout up around maligned American genres like 1980s pop-metal.
 

At the same time, Japan's baby boomers grew up hearing American jazz and rock—giving bands like Kiss nostalgia power. Japanese record collecting also is rooted in a national fixation with connoisseurship, says Carolyn Stevens, a professor at Monash University in Australia and author of "Japanese Popular Music." In a competitive environment, record buyers are discreet. Mr. Oppermann says he escorted his Japanese client on a record-buying tour earlier this month, visiting the homes of collectors in Marin County, Sacramento and San Jose. He wouldn't say what the man bought or from whom. He said the man declined to be interviewed.
 

Bud Nemier, a San Jose dealer, says an unnamed Japanese buyer bought 200 records from him around that time, mostly easy-listening and 1970s rock.
"You know how they say in real estate it's all about location, location, location?" says Mr. Oppermann. "Here it's all about condition, condition, condition."