After the First Continental War, the world, which came to a standstill with nuclear weapons, is divided with tension between the Western-Japanese bloc and the Eurasian Union.
The Far Eastern nation of Neo-Japan, though spared from the battlefield, has rapidly reorganized its cities, economy, and society under the guise of post-war reconstruction. While outwardly prospering as a futuristic city, internally, disparities, surveillance, corporate control, and information warfare are progressing.
Under the banner of "Salvation through Technology," the government is promoting the prosthetic body project. While prosthetic technology has developed as a countermeasure for war wounded, disabled individuals, the elderly, and labor shortages, in reality, the human body has become commodified, with constant suspicions of experiments on the poor and orphans, military applications, and neural data collection.
While prosthetic bodies grant abilities beyond human capabilities, a stratified society has emerged where the wealthy rely on safe, high-performance prosthetics, and the poor are left with shoddy used parts. Illegal modifications, underground medicine, prosthetic drugs, and illicit modules form a black market, deepening the conflict between biological humans and augmented individuals.
The prosthetic industry is dominated by three major corporations.
Kourei Group is a Eurasian company supplying affordable, high-output parts.
Helios Biosystems is a Western company monopolizing high-end medical prosthetics.
Amaterasu Heavy Industries is Neo-Japan's largest corporation, tied to the government, and is suspected of managing citizens' physical information and behavioral data.
The capital, Neo-Tokyo, has a three-tiered structure. The upper Central Layer is a managed city where the government, corporations, and high-end medical facilities are concentrated. The Middle Layer is the living space for ordinary citizens. The Outer Layer is a neglected slum rampant with illegal modifications and criminal organizations.
Prosthetic bodies have a rear maintenance hatch, concentrating the main power supply, neural connections, cooling systems, auxiliary AI, and power lines. While high-performance, regular maintenance and neural synchronization are essential, malfunctions or synchronization errors can lead to serious accidents.
The most significant mental illness in the prosthetic society is Echo Dissonance Syndrome, or EDS. It is a disease where the brain, having its sensory input replaced by artificial signals, loses its sense of self, leading to depersonalization, emotional blunting, loss of empathy, self-harm, and violent impulses, culminating in ego dissolution and indiscriminate destruction in its terminal stages. Corporations conceal the incidence rate, and terminal patients are treated as disposal targets rather than patients.
In this world, cyber warfare through prosthetic neural ports also constitutes a significant form of violence. Physical connection risks data theft and loss of bodily control. Having one's prosthetic body hijacked is akin to having one's limbs controlled by another, treated with a fear greater than physical assault.