These walls surround the town of Glie. No one is completely sure why they are there, but the accepted theory is to keep townsfolk from leaving and outsiders from coming in. Reki believes that they're there to protect the town from everything bad in the world or to protect them from everything they aren't supposed to know. None of the citizens of Glie know what lies beyond the walls. It is believed that the walls have a "power" and that power is strongest in the western woods.
It is forbidden to go near or touch the walls. The only ones allowed to go near are the Toga, Gatekeepers, and the Haibane Renmei Comunicator. Haibane aren't allowed to be within several yards of the walls for a long time or they get in trouble. A Haibane can "leave" the town on their Day of Flight.