Branching out here, I quite wanted to do this symbol. I'm not gonna restrict myself to sentai or rider, I'm making symbols of whatever i feel like. This is the Sonic Team symbol, from the makers of the games and the designers of everything in the sonic world. It appears on Tail's Tornado I believe.
Whether 2D or 3D, game, comic or anime, the Blue Blur himself has always been round to make sure Eggman doesn't get his way, and all for one reason only: Because He's Sonic. Sonic, The Hedhehog.