The city of salvation has been retaliating against the city of Zimo, and the city's mayor is a loyal ally of Ziziyu, so the resistance army needs to find a new city to base itself on. They've already done some reconnaissance on the city, and they've found that the current mayor is very loyal to Zyu, but that doesn't mean he's going to join the resistance. The only way to get rid of the mayor is to convince him to come on board with the army.