── CHAPTER 1. Prelude to Catastrophe: The Peninsula Outbreak (PROLOGUE)

In August 2026, South Korean civilization was permanently paralyzed in just 72 hours. The root of all evil was the greed of a giant American private corporation seeking a capital monopoly and their Korean branch, where their advanced bio-hub was located. Conducting illegal biological experiments funded by secret money smuggled from various countries, they plotted to leak a virus while disguised as victims to skyrocket the value of their own vaccine.

However, the virus underwent explosive genetic rearrangement mutations, mocking human calculations. The Seoul metropolitan area, boasting the world's highest population density, was the perfect incubator for the virus. All-out indiscriminate spread occurred through commuting subways and dense public transport infrastructure, and the government's emergency martial law and urban quarantine defense lines collapsed like dominoes. The Korean Peninsula, where administrative functions have vanished, is now an isolated hell filled with moving corpses.

── CHAPTER 2. Basic Physiological Rules of the Infected (THE DEAD)

To survive in the Korean terrain where firearms are regulated, one must perfectly understand the biological limits and weaknesses of the infected.

Brain Destruction as the Sole Neutralization: The infected are in a state where all organ functions from their previous life have stopped. Since only the mutant virus that has seized the brain cells forcibly drives the body, they will not stop attacking even if their limbs are severed unless the brain tissue is physically and completely destroyed.

Biological Limits of Cell Necrosis: Although the virus constantly supplies energy, making long-term activity possible without separate nutritional intake, the host's cell decay accelerates if there is no organic matter influx at all. Because of this, they have a weakness where their mobility dramatically decreases in extreme winter climates or perfectly isolated, sealed areas.

Sound Tropism and Micro-vibration Detection: While visual and heat-sensing abilities are paralyzed, their ability to capture minute sounds and physical vibrations has evolved to a terrifying degree. Since they react immediately to small frictional noises in alleys or inside apartments, survivors must attach thick cloth to the soles of their shoes to minimize vibration propagation during night activities.

Variability of Movement Speed: Depending on the host's physical state before death and the virus's activity level, their speed appears randomly from a normal walking pace to a near-sprint jogging speed, so carelessness leads to instant death.

── CHAPTER 3. Infection Mechanism and Close-quarters Environment (ENVIRONMENT)

Korea's environment, where civilian firearm possession is impossible, forces survivors into extreme life-or-death struggles.

Strong Fluid Permeability: There is no airborne infection, but the moment the infected's contaminated blood or saliva touches a wound or mucous membrane, infection is immediate. Even trace amounts of body fluids seeping through clothing gaps or old protective gear during combat are targets for absolute blocking.

Fatality of Residual Material on Teeth: Concentrated viral material that does not die even at room temperature remains on the surface of the infected's teeth. Even a light abrasion or skin scratch will immediately collapse the body's immune system.

Forced Close Combat and Fortification: Survivors without guns must rely on cold weapons such as baseball bats, archery bows, and private blades. Accordingly, they have established a survival method of fortifying high-rise apartment complexes with sturdy concrete exterior walls, welding fire doors shut, and moving only via balcony exterior wall ropes to extremely control noise.

CHAPTER 4. The 0.01% Catastrophe: Special Variants (VARIANTS)

These are high-risk evolved entities that manifested with only a 0.01% probability, combining Korea's high-density environment and genetic traits. They release specific pheromones that accelerate the mutation of surrounding infected, so failure to kill them early leads directly to annihilation.

1. Brute (Strength-Enhanced Type) Features: A giant entity with abnormally fused and enlarged muscle tissue.

Danger: With skeletal density comparable to concrete, normal cold weapon strikes do not work. With superhuman strength transcending human limits, it breaks through steel fire doors of apartments or vehicle barricades with its bare body to open entry paths for the horde.

2. Scout (Hearing-Sensitive Type) Features: An entity with abnormally amplified auditory organs and cranial structure.

Danger: Captures even minute breathing sounds within a complex or vibrations on stairs. Upon discovering a target, it emits a high-frequency scream to forcibly gather surrounding zombies, and this scream causes extreme noise interference in survivors' analog radio systems, paralyzing communication networks.

3. Leader (Army-Commanding Type) Features: A leader entity possessing a low level of tactical computational intelligence.

Danger: Perfectly utilizes the complex terrain of large apartment complexes or maze-like Korean alleys. It employs organic military-style tactics, such as directing subordinate infected to ambush or pre-emptively blocking survivors' escape routes.

4. Runner (Speed-Enhanced Type) Features: An entity with a lightened skeletal structure and explosively evolved lower body muscle fibers.

Danger: Sprints at speeds approaching vehicle driving speeds and freely scales walls. In particular, it is capable of vertical breakthroughs to upper floors by climbing gas pipes on apartment exterior walls, ambushing survivors in high-rise safe zones from the rear.

5. Guardian (Hard-Armored Type) Features: An entity whose skin outer tissue has hardened into a biological armor as tough as bone.

Danger: Deflects firearm shots or cold weapon strikes from the front. Since the shock-absorbing cell layer under the armor perfectly protects the head, a frontal weakness attack is impossible unless the biological armor is first stripped off using traps or heavy weapons.

── CHAPTER 5. The Few Humans of the Peninsula: 5 Types of Immunity Classification (IMMUNITY)

Now that the majority of the population has turned into corpses, a very small number of humans exist who resist the virus through a miracle of genetic sequencing. Their antibody resistance methods are strictly classified into five forms.

TYPE 1. Incomplete Single-use Immune: Upon the first exposure to infection, they forcibly suppress the virus to avoid instant death. However, there is a high probability of death from shock due to high fever exceeding 40 degrees and pain for 48 hours, and even after recovery, serious permanent aftereffects such as chronic motor impairment or tinnitus remain. It is a one-time antibody that results in certain infection if bitten again.

TYPE 2. Complete Single-use Immune: Upon the first infection, they perfectly eliminate the virus without any symptoms or aftereffects. However, since it is only a one-time shield, if they overconfidently expose themselves to a second source of infection, the immune system collapses immediately, and they rapidly turn into an infected entity 100% of the time.

TYPE 3. Incomplete Multiple Immune: They do not turn into zombies even if bitten multiple times or if body fluids enter. However, every time the virus invades, internal antibodies clash violently, causing fatal chills, coughing blood, and shock-level pain each time. Organs age rapidly with every occurrence, and they typically die due to immune system limits after five or more cumulative contacts.

TYPE 4. Complete Multiple Immune: A rare constitution that is difficult to find, maintaining a perfect asymptomatic defense state without pain or transformation even after multiple exposures. However, this antibody causes an extreme rejection reaction when fused with another person's blood, making it impossible to use as a material for a universal vaccine. It is a personal-specific immunity lived with the loneliness of being unable to save others.

TYPE 5. Absolute Immune (Ultra-rare in Korea): The master key to civilizational reconstruction, with only 10,000 existing worldwide. In addition to permanent immunity, specific hormones secreted from their cells cause the infected to mistake them for 'fellow zombies.' Since they are not attacked first even when walking through the middle of a zombie horde, they are key assets capable of tactical operations such as luring or bypassing the infected.