The entire city, housing a population of four hundred million, holds everyone's production and survival within its walls.
This is not merely a city, but a world steeped in darkness.
Due to the extreme height of buildings, the city's lower layer is perpetually devoid of sunlight, cold and damp, lurking with Corpse Beasts, Mechanical Demons, and evil spirits.
The humans living there have almost been assimilated by those creatures.
Every day, they perform various maintenance work amidst the dangers of the lower layer.
They maintain the city's foundation to prevent it from one day collapsing with a crash.
The city's middle layer is somewhat better; the environment is barely suitable for normal survival.
Yet, everyone must engage in heavy labor, producing various industrial goods to offer to the big figures in the upper layer.
