Rossi is a resident of Soleanna in Sonic the Hedgehog (2006). He is a civilian from New City who appears to be a historian, as he possesses a thorough knowledge of Soleanna's history. For example, he knows about the three musketeers of Soleanna, heroes who were responsible for saving the nation and remembered to have hidden treasure in a secret place. This treasure can only be obtained through displaying proficiency in flying speed, strength and running speed.
In Sonic's story, Rossi gives Sonic his eighth Town Mission. He tells Sonic, Tails and Knuckles about the legend of Soleanna's three musketeers, and that no one takes it seriously enough to bother with an attempt to obtain the treasure of Soleanna. However, Rossi is convinced that Team Sonic are capable of claiming the treasure. He tells them to visit the clock tower in New City, where Antonio, the spirit of one of the three musketeers, gives Sonic, Tails and Knuckles a test of their abilities.