An amazingly-dedicated Jet Set Radio fan has reverse-engineered how models are stored in the game and worked in a tool to replace them. Here's them playing as Sonic and Mario:
The user has also other videos playing as Professor K. and other non-playable characters in JSRF. You should check those videos out! There's also a blogspot with information on how to do this and import other models: http://jsrf-inside.blogspot.com/
The user has also other videos playing as Professor K. and other non-playable characters in JSRF. You should check those videos out! There's also a blogspot with information on how to do this and import other models: http://jsrf-inside.blogspot.com/