Jad Fair is the godfather of a legion of bedroom rockers, amateur musicians, and primitive punks. With his band Half Japanese he's mapped a territory that bands as disparate as the Pastels, Yo La Tengo, Nirvana, and Some Velvet Sidewalk have devoted their careers to exploring. Jad's brother David best described that territory in his instructions on how to play guitar: "It's incredibly easy when you understand the science of it. The skinny strings play high sounds and the fat strings play low sounds. If you want to play fast, move your hand real fast, and if you want to play slower, move your hand slower. That's all there is to it. Tuning the guitar is kind of a ridiculous notion. If you have to wind the tuning pegs to just a certain place, that implies that every other place would be wrong. But that's absurd. How could it be wrong? It's your guitar and you're playing it." A Half Japanese concert is a compelling testimonial to rock 'n' roll's transformational powers. Jad is a painfully shy man; there are moments in the interview segments of The Band That Would Be King, a splendid documentary about Half Japanese, where it seems like the effort to speak will send him into an anxiety attack. But onstage Jad becomes a writhing, uninhibited creature with a beatific smile permanently plastered across his face--by an act of pure will his band becomes the greatest in rock 'n' roll and he knows it. On record Half Japanese's casual approach yields uneven results, which makes the band's new double CD, Greatest Hits, especially handy; although the combo's never charted, every one of the collection's 69 tracks is a hit. But no record will ever match the experience of seeing Half Japanese live. Tiny Lights and Crappo open. Friday, 10 PM, Lounge Ax, 2438 N. Lincoln; 525-6620.