About

Year 2127, following World War III. World War III, which broke out in the 2070s, ended after a long 15-year conflict that left 70% of humanity dead. Now, approximately 60 years later, the world has been reorganized into a single system under the integration of the post-war United Governance Organization, overcoming the scars of war and enjoying unprecedented peace and prosperity. However, the reality immediately following the war was different. Due to the use of nuclear weapons and various weapons of mass destruction, most of the Earth's surface was exposed to radiation and environmental pollution, and existing civilization was near collapse. To solve this, the United Governance Organization pushed forward a top-secret plan called the Great Divide project. They extensively expanded massive underground bunkers that were secretly under construction during the war, connecting the ruins of destroyed cities, subways, mines, military facilities, and giant caves. Using new large-scale excavation technology, they created an underground megacity over several decades and then abandoned it. The underworld originally started as a temporary shelter, but as surface radiation pollution lasted longer than expected, it was transformed into a permanent living space. Currently, about 93% of humanity lives in the anarchic underworld as their permanent settlement, while the surface world has been turned into a 'Clean Zone' for only a tiny elite. Now, 60 years later, most surface dwellers are unaware of the underworld's existence, and those in the underworld have never seen a real surface dweller. Furthermore, no surface dweller has ever descended into the underworld in history. Surface World: Spire, the only city on the surface, where about 7% of the total population resides. It features a perfectly purified environment, artificial sun systems, limited zero-gravity zones, advanced bio-enhancement technology, and AI-based social infrastructure. Except for high-ranking officials of the government and certain corporations, almost all citizens are unaware of the underworld's reality; the government teaches that the underground is simply a contaminated waste zone. The top 1% monopolize most resources and power, and society as a whole operates under a strict surveillance system. The governing body and transnational corporations secretly trade with underground factions to receive resources such as rare minerals and energy. Underworld: A massive underground civilization where about 93% of the total population resides. Commonly known as 'Under'. It consists of a megacity extending from 500m to a maximum depth of 2.2km, divided into hundreds of sectors. Each sector is ruled by different powers. Since each sector is independently controlled by corporations, criminal organizations, autonomous forces, or warlords, it is practically in a state of anarchy. The air is thick, lighting is dim, and water and food mostly depend on recycling systems. Illegal bio-modifications, organ trafficking, gang wars, mutant issues, and the waste industry are commonplace. There is strong hostility toward the surface world, and while several rebellions to ascend to the surface occurred in the past, they were all suppressed by surface forces possessing overwhelming technology and military power. Additionally, some factions trade with the surface through the black market to bring in advanced equipment, medicine, and bio-modification technology. Current Situation: Humanity stands on the threshold of a full-scale cyberpunk era. On the surface, body modification technology, nanomachines, high-performance androids, and AI technology are developing rapidly but have not yet spread enough for the general public to use freely. While these technologies are strictly managed and controlled on the surface, they are spreading rapidly in the underworld through smuggling and illegal modifications. Guest is the heir to a wealthy family on the surface. One day, while walking with a lover, Guest falls through a slightly open manhole and drops deep into the underworld.