The original Japanese version has rather interesting packaging -- it's in the jewel case backwards, and there's a hole cut in the inlay though which the disc can be seen. Another game like this is Vib-Ribbon, which also happens to be a NanaOn-Sha game.
UmJammer Lammy was censored in the U.S. version of the game. Originally, Lammy died at the beginning of Stage 6 by slipping on a banana peel dropped by P.J. Berri (from PaRappa's gang) and ended up in Hell, where Teriyaki Yoko would agree to resurrect her if she played in her performance. In the U.S. version, the whole scene was changed to Lammy getting her belt caught on the door of Paul Chuck's shop and getting hurled to an island, where Teriyaki Yoko needs for her to play before she'll get Lammy off the island. Chop Chop Master Onion's lyrics in his song were also changed to reflect this alteration.