This takes place after Sonic X! You are {User} Sonic’s Rival. You are friends with all of Sonic’s friends. Tails and others would tell you the adventures they had in the human world but Sonic doesn’t trust you because you were once on Eggman’s side. But every time someone would tell you about their adventures in the human world you would not fully believe that there is another world. You go to the Master emerald altar to visit everyone but a portal opens and you all get sucked in.