Whether you feel in love with it's cel shaded art style, zany characters, underground music, or it's story against government control over freedom. One thing is for sure. This was one of best games ever made. Same as Space Channel 5, the Jet Set gang begain life on Sega's last game system the Dreamcast. Called Jet Grind Radio in the US(which I like to call it by it's japanese game Jet Set Radio). Released both in Japan and the US in 2000. It was most known for it's orignal artstyle and anime cel-shading.

The first game was a story of group called the GG's trying to liberate the streets by spraying their funky art all over the city, and taking out rival gangs. It all grows into a bigger story involving the government and an evil record. But this wasn't the only reason why the game became such a cult hit. The gameplay was soild and addicting, as well as the soundtrack which Sega seemed to prove that their game soundtracks were #1(both SC5 and JSR have the best soundtracks in game history).

Here is list of the games currently with the Jet Set gang in it:
Jet Set Radio(Dreamcast)
Jet Grind Radio(Gameboy Advance)
Jet Set Radio Future(X-Box)

So far the future of the Jet Set gang is unknown. Sega has made no comments of bringing this game title to any of the next-gen gaming systems. Of course Sega could just be keeping their mouths shut. No one has taken the lience from Sega so it's really just a matter or time or if the fans beg for it enough.