The Demon situation appears hand down tamed, but Bittore can't risk for them to bash through the walls if more decide to come through that portal of which apparently wasn't destroyed. As far as Bittore theorized, that portal was just covered with Dirt and rock, it wasn't smashed or blown in to bits.
However, she can't risk for Demons to catch them off Guard. For example if the Demons appear at night when everyone is asleep, it would indeed be a terrible situation for this tribe to find their selves in. Even if they manage to tame the situation, there surely will be several victims at least.
So she came up with a solution, Fire Controlling ladies will take shifts to Guard the walls. They are the most vulnerable now that there aren't even 3 walls built so the whole tribe has to be secured right now. 8 Fire Controlling ladies have been assigned to Guard the walls!
