"I see capsule as a J-pop group, but then again, I don't think J-pop should be made into a particular genre with its own rules," says Yasutaka Nakata of electro unit capsule and producer of idol sensations Perfume. "There are professional producers who try to create 'J-pop music,' but really any pop music made in Japan should just be considered J-pop."

With the release of "World of Fantasy" on May 25, their 12th original album, Nakata and capsule vocalist Toshiko Koshijima have had 10 years' worth of releases on which to hone their particular vision of Japanese pop, beginning with the post-Shibuya-kei technopop Japonica of 2001 single "Sakura" and culminating now in the relentless 128-BPM electro-house thumping of the new album. However, of the decision to restrict himself to such a strict rhythmical limitation, Nakata just laughs.

"It was like a game rather than any kind of grandiose concept," he explains. "Like when you were little, you might try to see how long you could hold your breath."