Ami Onuki and Yumi Yoshimura have been known in Japan since 1996 simply as "Puffy." They sensed a cross-over market in the USA for their quirky brand of humor and tightly crafted pop, and did a few short tours in "progressive" music centers like Austin TX.
Their 2000 release "Spike" was the first to be released simultaneously in Japan and also in the USA with several tracks re-recorded with English vocals. Sean Combs decided that this would be an opportune moment to SUE the girls for using the name "Puffy," so a compromise was reached. In the USA, they are known as "Puffy AmiYumi." Redundant, yes, nbut it kept them out of court.
Almost IMMEDIATELY after making the change, Combs STOPPED calling himself "Puffy" or "Puff Daddy" and started going by the "P. Diddy" name. Nice guy.
ANYWAY...looks like a very cool show. The Web Site is wild, and a fun time-killer...lots of Flash animation, show clips, and concert clips:
http://www.cartoonnetwork.com/tv_shows/puffyamiyumi/