By MATTHEW ZUCKERMAN, Special thanks to The Asahi Shimbun

Most people will have already made up their minds about the significance of the upcoming visit to Japan of the Backstreet Boys.

If you are a music fan (probably female) of a certain age (probably between 12 and 16), you will likely think them the most appealing collection of young men in existence. If you are much older, then you have probably filed them as yet another boy band polluting the air with their disposable pap.

The truth, as with most things, is somewhere in the middle.

Back in the early 1940s, the young Frank Sinatra was the first singer to mobilize the mass teenage market, and a decade later, he was also the first singer to make the transition to a more mature style of music and audience. Ever since, it has been a tough challenge for singers or bands to graduate from teenybop icons to a wider market. The bargain bins are full of musicians who failed to make the leap.

The Backstreet Boys-comprising Kevin Richardson, Brian Littrell, Howie Dorough, A.J. McLean and Nick Carter-were signed to Jive Records in 1994, and any 14-year-old fans who bought their debut album, released the following year, will now be 20. This means that these fans, or ex-fans, could be in college, working in an office, married with kids, serving in the armed services-or any permutation of these.

So what does a maturing band of teen icons do to keep its fanbase? The four album releases to date by the Backstreet Boys-their eponymous first album, followed by ``Backstreet's Back,'' ``Millennium'' and this year's ``Black & Blue''-all share similarities with the music of Boyzone, Britney Spears and 'NSync, although the BSBs offer a little more in the way of credible hip-hop, R&B and dance-club pop, making the transition to more adult-oriented music less of a gulf than one would imagine.

The band's latest album tends more toward the teen pop ballad side of their repertoire than such upbeat hits as ``Everybody'' (from ``Backstreet's Back''), and it has fared less well in the charts than the monster-selling ``Millennium,'' but it still puts them ahead of their competitors. Of course, Max Martin, the man behind many of their hits, is also responsible for hits by Spears and 'NSync, but Brian in particular is taking on more of the writing credits, and the task of continuing to appeal to their fast-maturing fans while garnering new teenage followers looks to be less insurmountable than it does for Britney and her ilk.

The main problem the band has faced of late is the well-being of A.J., who recently entered rehab for alcohol abuse, depression and anxiety. The singer's mother, Denise McLean, has stated that her son is a very different character in private to how he is when he plays the part of a worldwide pop sensation, and the pressure seems to have got the better of him.

The latest news is, however, that he has made a full recovery, and on Aug. 24 the Backstreet Boys returned to the stage in Milwaukee with a performance that reassured the band's, and in particular A.J.'s, fans. This November, their whistle-stop stadium tour of Japan will take in Tokyo, Nagoya and Osaka and sell-outs are expected.

Next month sees the release of ``Chapter 1,'' the BSB's first greatest hits collection. The Japanese and European editions will feature a few more tracks than the North American releases and would therefore seem to be the ones to get. The album will be accompanied by a VHS and DVD release, and the collection will feature at least one new track, ``Drowning,'' which will be released as a single on Sept. 17.

The question now is whether this summation of what the Backstreet Boys have so far achieved will be a springboard to-as the title suggests-a new chapter, or the charting of a career that tails off as fans move on to richer and wilder pastures.

Only time, of course, will tell, but if any of the present glut of boy bands is to survive far into the new century, my money would be on A.J. and his colleagues.

The Backstreet Boys will perform from 6:30 p.m on Nov. 19, 20 and 21 at the Tokyo Dome (03-5800-9999) near JR Suidobashi Station, from 5 p.m. on Nov. 23 at the Nagoya Dome (052-719-2121) and from 5 p.m. on Nov. 15 at the Osaka Dome (06-6586-0106). Tickets cost 8,500 yen and 7,500 yen. For details, see .