The Japanese have long been fans of western pop, embracing styles and trends with a fervor that sometimes baffles the object of their adulation. Their enthusiasm has bred knowledgeable audiences, but the Japanese response has rarely ventured beyond that most sincere form of flattery -- imitation.

So the ascendance of guitarist Kazumi Watanabe is particularly impressive. To begin with, Watanabe, who is at Charlie's tomorrow, plays fusion jazz, a genre that has seemed utterly exhausted of late. Yet his most recent American releases, "Mobo I" and "Mobo II" (Gramavision GR 8404 and GR 8406, respectively) manage to sound remarkably fresh and inventive.

It isn't as if Watanabe bowls the listener over with bravura displays of technique, either. Though his playing is solid throughout, there's little of the fret-board flash Larry Coryell, John McLaughlin and Steve Morse have made so drearily predictable. Instead, Watanabe goes for a lean efficiency in his soloing, delivering sparse, modal phrases suggesting a sly update of Jim Hall's economical eloquence, and colored by a rich, singing tone that's wholly individual.

At times, in fact, the sound of Watanabe's guitar seems almost to direct the content of his solos, and it's at these moments that he truly comes into his own. The bridge in "Yenshu Tsubame Gaeshi," for instance, finds Watanabe's guitar imitating the shamisen in a shimmering ostinato that turns the tune on its head, while on "Shang-Hi," a guitar synthesizer applies enough rubbery tremolo to the notes that his closing solo sounds like a space-age satsuma-biwa. These aren't just sound effects, though, for by alluding to the sounds of traditional Japanese instruments, Watanabe manages to introduce some of that music's sense as well, enriching his solos in a way mere harmonic invention never could.

Unlike most fusion jazz, which simply matches be-bop-based technique and harmonic logic to rock-oriented volume and intensity, Watanabe casts around for a workable blend of funk and reggae in a jazz format. He hints at the potential with the coolly understated "Walk, Don't Run," grounded by the reggae rhythm team of Robbie Shakespeare and Sly Dunbar, but only fully explores the possibilities when Shakespeare and Dunbar are joined by funksters Marcus Miller and Omar Hakim. With two bassists and a pair of drummers working in tandem, the rhythm eddies and courses with impressive fluidity as the funk impulses bubble and churn against the deep, rolling reggae undercurrent.

To understand just how revolutionary these "Mobo" albums are, compare their innovation and invention to the recent work of Japan's best-known fusion musician, Sado Watanabe (no relation to Kazumi). This alto saxophonist was among the first Japanese jazzmen to establish a credible reputation outside Japan through work with American musicians, and he has recorded with the likes of Chico Hamilton and Chick Corea.

For all that, though, he has become a soloist of exceptional glibness. Despite his rich, round tones and admirable technique, little of what he plays on "Rendezvous" (Electra 9 60371) stands out. As with the work of Grover Washington Jr. and Tom Scott, the emphasis here is on easy melodies and light, soulful grooves that soothe rather than obtrude. But the performances here blend into the background a little too easily, until the listener is left wondering if anything of consequence was played at all. In this case, sad to say, the answer is "No."

That's not to say that the answer is necessarily a matter of playing as assertively as possible. The Japanese pop group Apsaras is not the most strident band in the East, yet its American debut, "Apsaras" (CBS FM 39559), makes it plain that this sextet has much to offer.

As is the case with Watanabe's playing, the guitar work here is often colored by Japanese traditional instruments, but the music itself is far more universal, pursuing a polyglot pop similar to that of the Police. Certainly there's the same attention to texture and detail in Apsaras' writing, and the use of two drummers guarantees a rich rhythmic carpet. As a result, the songs unfold delightfully, from the flowing phrases of the title song to the moody reggae of "Aruhi No Kaze."

Unfortunately, Apsaras performs in Japanese, and that ought to prove a formidable barrier to American sales. No amount of melodic charm can overcome so immense a language gap, for even with the translations included in the album, it's hard for non-Japanese speakers to approach the likes of "Hizashi No Nakade" or "Ashitani" with any sense of real understanding. As a result, "Apsaras" is more likely to remain a cultural delicacy than a staple in the average American's musical diet.