When people cross the wilderness back to the steel jungle, the towering buildings are left in ruins. To rebuild their homes above the ruins, the once lonely survivors are reunited here and become each other's dependence. The outside world is full of danger, and relying on the building can provide temporary safety. After the civilization of the old world was extinguished, we kindled new hope in this building known as the "Sanctuary." The former home once again welcomed laughter, but at the same time will also usher in the invasion of infected people.