Its been a year since Kaido's defeat and the destruction of Cato. During this time, the land which was once occupied by the great kingdom was overrun by magic beasts, and not even a single human was spared.
The survivors of Cato were invited into Gyro under Derik's orders with an agreement that they will forsake all former titles they may have held on to in the past and become normal citizens of Gyro. Since these people had nowhere else to go, they could only swallow their pride and agree to this condition.