Mother Keeper, No.6 Recommendations
Both series are set in a future where the world has become uninhabitable except for a few select places. Privileged people live within a walled city where they are ignorant to the lives of others living in the slums outside. In No.6, Shion is one of the privileged living in the wall. In Mother Keeper, Ricalna is one of the rebels living in the slums outside. In both series the protagonist ends up on the other side of the wall and learns that life there isn't what they expected and that everything they have thought to be true might be a lie.