hen it comes to hip-hop culture, Japan may as well be Mars. Which is why some of the weirdest, most interesting specimens of the music have sprung from the land of bukkake and vending machines offering teenage girls' soiled panties. For proof, check the output of mavericks like Audio Sports (a '90s group featuring Nobukazu Takemura and Boredoms' EYE), DJ Krush, Major Force, Cappablack and DJ Sushi.

But none of those outstanding artists has pushed hip hop farther out than Riow Arai. "Who?" I hear 98 percent of you asking. It's not surprising that many people slept on Riow's stunning experiments with hip hop's DNA. Mind Edit originally came out on Japan's tiny Soup-Disk imprint in 1999; Dutch East distributed the album in America, but only the most clued-in heads snapped it up before it went out of print. Two Riow cuts off his even scarcer Circuit '72 album also appeared on the excellent 1998 compilation Out Of Perspective (on Soup-Disk; it's a fine primer of late-'90s Japanese hip hop, by the way). So unless you make regular record-shopping excursions to Japan or obsessively monitor eBay, you likely haven't been able to hear Riow's output.

But now, thanks to England's exceptional Leaf Label reissuing Mind Edit, you can experience one of the most innovative hip-hop opuses ever to emanate from outside the US. After a brief teaser of atmospheric hip hop, the disc begins properly with "Undulation," and immediately we're forced to recalibrate our expectations of hip-hop albums. Riow's thudding, off-kilter beats power through a field of stereopanned jet-takeoff sounds, resonating Asian bells and staccato bursts of angular guitar. The effect's as disorienting as a Tokyo subway station at rush hour.

Riow keeps you off-balance with the 70-second "Inter," whose explosive, stuttering beats and fractured editing predate Prefuse 73 similar exercises by about two years. (I'm not saying Scott Herren bit Riow's style; I'm just noting that the Japanese cat deserves props for initiating an aesthetic Herren's parlayed into a lucrative career. That said, I remain a huge Prefuse admirer.) "Break Roads" and "Trillion" further Riow's equilibrium-upsetting agenda. On the former, Riow uses warped wah-wah organ, tricky-metered beats, and razor-sharp guitar accents, maximizing minimal ingredients and utilizing space like a feng shui master. "Trillion" is a quirky, methodical funk juggernaut that makes you feel like you're in a Robitussin-induced stupor. (The only ordinary moment on Mind Edit is the closing cut, "I Dine At Daybreak," and it's a real head-scratcher. After all Riow's radical skill-flexing, it's disappointing to hear this chilled, vibes-heavy downtempo track, which sounds like filler from a Thievery Corporation DJ set or something equally innocuous. But one mediocrity to 10 gems is a way better ratio than most producers muster.)

While Riow's production definitely skews toward radical invention, he rarely forgets that, no matter how odd the time signature, hip hop needs the funk like America needs oil. In this way he reminds me of British iconoclast Req, another hip-hop minimalist who makes old-school breakbeats sound alien while retaining their innate phatness. Not many artists can pull off this difficult feat, and that's why we should treasure artists like Riow (Takemura, Coldcut's Jonathan More, Si Begg and BBC radio jock John Peel consider themselves fans, which ought to be a ringing endorsement for the rest of you).