TOKYO -- Musicologists will continue debating the point for ages to come, of course, but among contemporary scholars the consensus holds that the real beginning of the cordless-electric-hand-drill genre of rock guitar was Paul Gilbert's seminal 1990 composition "Daddy, Brother, Lover, Little Boy (The Electric Drill Song)."

As a distinguished professor at California's Guitar Institute of Technology and lead guitarist of the hard-rock band Mr. Big, Gilbert was naturally adept at the "two-hand tapping" school, in which guitar and/or bass players tap the strings frenetically with all eight fingers, creating a frenzied, stuttering music that sounds something like Porky Pig reciting the Gettysburg Address.

But this style was archaic -- dating back to the early Hendrix era -- and technically stultifying for Gilbert, because there was a limit to how fast his fingers could tap the strings. How could you accelerate the tapping? While pondering this problem, Gilbert happened to walk through a hardware store, where he saw a small electric drill. Eureka! He glued a guitar pick to the end of the drill bit, turned on the power and plunged the thing into his strings. The rest, as they say, is hysteria.

At least, it caused three weeks of near-hysteria among rock critics and screaming hordes of drill-rock fans the length and breadth of Japan last month when Gilbert and Mr. Big came back here for another triumphant tour of the country where Mr. Big is really, really big.

It's not that Mr. Big is small potatoes back in the U.S.A. The band topped the Billboard charts at home last year with its hit single "To Be With You."

But Mr. Big is bigger in Japan than anywhere else. The band's albums -- particularly "Live Raw Like Sushi" and "Raw Like Sushi II" -- sell better here than at home. Gilbert was voted "Best Pop Musician on Earth" the past two years by readers of the magazine Yangu Geetah (Young Guitar), Japan's equivalent of Rolling Stone. In his column for Guitar Player magazine, Gilbert regularly quotes the hilarious fan letters he receives from Tokyo (e.g., "I love you guitar to dying.")

Gilbert has returned the favor, coming back here for repeated tours. In an open letter to his Japanese fans last year, Gilbert wrote: "We are very happy our song 'To Be With You' is number one in America. However, we played it live in Japan first ... Thanks again for being a step ahead and discovering Mr. Big first."

Mr. Big, of course, is hardly the only American talent to find success on this side of the world. Cars, cameras and cassette players are one thing, but when it comes to pop culture, the United States has a huge balance-of-trade surplus with the economic giant across the Pacific.

U.S. books and movies routinely stand atop the charts here; last year, 21 of the top 25 movies in Japan were American-made. U.S. musicians from Mariah Carey to Megadeth sell millions of CDs each year to the Japanese.

But that still doesn't explain why Mr. Big in particular has become so huge in Japan.

One reason is the inherent mystery of Japanese pop culture; Gilbert and his band are the beneficiaries of one of those inexplicable "booms" that sweep over this heterogeneous nation at regular intervals.

But Mr. Big's bigness in this small country is also, in a way, a tribute to the benefits of international trading -- as Gilbert himself noted during this tour.

To understand why, you have to go back to that crucial moment in the hardware store, when Gilbert first saw the hand drill and felt the moment of inspiration.

As it turned out, the drill that caught the composer's attention was made by Makita, a big Japanese power tool company.

That historic first drill -- now on permanent display in the collection of rock icons at the Los Angeles Hard Rock Cafe -- was Makita's Model 6012-HDW, a cordless hand-held tool that emits a truly eerie "Wheeee-ooowww" sound from its motor even before you stick the drill bit into the guitar strings. On recordings of "Daddy, Brother, Lover, Little Boy," you can hear that motor whirring just before Gilbert starts his guitar solos.

A young worker at Makita's factory in Aichi, Japan, happened to see a photo of Gilbert playing guitar with an electric drill and noticed that the machine in the great man's hand was a Makita.

Sensing a PR opportunity not normally available to companies that deal in power drills, band saws and lathes, Makita Corp. became Mr. Big's official sponsor, underwriting tours of both the United States and Japan. "For a Japanese power tool to sponsor an American rock band," declares a beaming Hiroaki Koreeada, an executive director at Makita, "that's unprecedented! That's unique!"

Even Makita's executives, however, seemed surprised to learn that in Paul Gilbert they got not only the world's best-known advocate of electric-hand-drill guitar-playing, but also an outspoken advocate of free trade.

At a press conference in Tokyo just before the recent tour began, Gilbert ran into tough questioning from a representative of the Baltimore Sun.

Why do you use a Makita drill? the reporter demanded. Why don't you use a good American drill, like a Black & Decker? After all, Black & Decker has a factory near Baltimore.

The rock guitarist was unfazed.

"In the first place, Black & Decker is a British-owned company now," Gilbert said. "And my Makita drill is made in the U.S.A.

"We try to avoid politics," he went on, "but in this international world, we are economically interdependent. With free trade, everybody wins. Makita makes a darn good drill, and we use it. And Makita has been good to us, so we can come over here and sell records.

"In our band, we all use Japanese instruments. We have Yamaha guitars and bass, Ibanez guitars, Tama drums. They're good instruments. If it's good, we want to use it. And we can, because of open world trade."

In a nation that lives by its exports, of course, all that amounted to preaching to the choir -- and probably served to enhance Mr. Big's stature here.

When the band played to an overflow crowd at Tokyo's Showa Women's University, for example, the fans -- mostly college kids, with a smattering of thirtyish "salarymen" and "office ladies" -- spent the whole evening shouting "Do-ree-ru! Do-ree-ru!" -- which is about as close as the Japanese can get to pronouncing the English word "drill."

Mr. Big had its drills onstage, but in fact the power tools were only used on two or three songs. One Makita drill had three guitar picks mounted on the end of its bit. Gilbert used that one for a quick riff on the Jimi Hendrix tune "Hey, Joe."

The crowd erupted in new outbursts of enthusiasm whenever the hand drills came into play. And when the band finally closed the evening with a drill-assisted rendition of its song "Woman From Tokyo," the audience paid Paul Gilbert the ultimate tribute.

They started throwing things onto the stage. Not flowers, not panties, not hotel keys. Instead, the Japanese fans threw Paul Gilbert their digital watches.

Special correspondent Yoshihiro Nakayama contributed to this article.