On the surface, it is a modern city in the 21st century, but the world has long been invaded and "mimicked" by a kind of high-dimensional creature called "alien beast". Cities, buildings, and even 99% of "human beings" are forged by alien beasts in order to capture and "harvest" humans. Real human beings are imprisoned in false daily life, like crops in a greenhouse. The entire world is a huge "mimicry farm" built based on human memory and cognition.
