Yup, Naoto Oshima left Sonic Team because Yuji Naka was xenophobic which was why Naka went to America, and no one on Sonic Team liked Naka which is why a bunch of them all left Sonic Team to join Prope with him.
It's all starting to come together now.
Originally Posted by Sega1991
In 1996, Sega of America wanted to use the NiGHTS technology to make a Sonic game for the Sega Saturn (the game being Sonic X-treme). Yuji Naka threw a temper tantrum and threatened to quit if the American developers got to use his NiGHTS code. Some say this was the move that killed the chances of a real Sonic game on the Saturn being produced.
Internet urban legends are awesome