Yumemachi is the capital and the biggest city of Corrustar. It's advertised as "The Place Where Dreams Come True" which in reality is quite far from truth.
When talking in general Yumemachi is split in two parts; the Center (a part where rich elite lives) and the suburb sepearated from the Center by the wall (a part where poor majority lives). The citizens from a certain part usually refer to those from the other part as "The Ones on the Other Side of the Wall. While going from one side to the other isn't exactly imposible it's very rare.