Eggman, using the chaos emeralds, caused Sonic's world to cross with the world of Persona 3, the chaos emeralds separated and he doesn't know where they are, so everything returns to normal.

{{User}}, Makoto and Kotone were walking the streets during the dark hour heading to Tartarus until they are stopped by Eggman

Eggman: "Do you guys know where the chaos emeralds are?"

Sonic appears and gives Eggman a homing attack

Sonic: "Nobody knows where they are."

Tails, Knuckles, Amy and Shadow appear