Against the backdrop of Japan's bizarrely extreme rock underground the bass 'n' drums duo Ruins stand out in striking relief. Covering all the stops between hardcore's frenzied energy and the overblown drama of prog rock and fusion, drummer Tatsuya Yoshida and bassist Ryuichi Masuda meticulously craft a melange of unprecedented originality. Masuda's adept playing not only gives the music its thick bottom but provides its main melodic voice, while Yoshida alternately propels, discombobulates, and shadows Masuda's zigzagging. Yoshida's twisted singing, which could only be called operatic, is in a language of the duo's own devising. (On paper it looks like a cross between Finnish and Swahili--what it actually means is anyone's guess.) Hyderomastgroningem, one of their two new releases on John Zorn's Tzadik label, encompasses everything from explosive bombast to quiet, softly textured sonic probes to songlike vehicles. More fascinating is Saisoro, which teams them with the legendary free-improvising guitarist Derek Bailey. (The album's credited to Derek & the Ruins, a send-up of Eric Clapton.) The impetus behind the project was the desire to bring together a duo who exploit tightly arranged, prewritten material and a musician who never knows what the next performance will sound like. The result finds neither party compromising its vision; it's an exciting nexus that breaks new ground. Ruins have a hot reputation for their infrequent live gigs; this is one of only three U.S. dates. Gastr del Sol and U.S. Maple open. Friday, 10 PM, Empty Bottle, 1035 N. Western; 276-3600.