The story takes place in New Hong Kong in 2187, a future world where technology is highly developed but society is severely divided. Giant corporations control the lifeblood of the city, and ordinary people live between steel and neon. Prosthetic modification technology has become popular, ranging from basic functional prostheses to military-grade combat modules. However, excessive modification can lead to "prosthetic body rejection syndrome" and eventually lead to mental breakdown. The city is divided into the corporate elite in the upper city and the lower class people in the lower city. As a special group, the homeless family walks on the edge of the law and has its own rules of survival and moral principles.
