The Hidden Laboratory

In the workshop, Ha Yul crawled ahead, feeling the vibration of the thin metal plate pressed beneath her palms. The duct remained narrow, and the stench from the corpse they had passed earlier clung to the metal surfaces, trailing after them. The two moved in silence for a while. The duct twisted several times before sloping gently upward. The texture of the air shifted. Inside the duct, it smelled like a beast's den. But after they passed the upper joint, an entirely different stimulus ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠seeped thinly over the filth. Disinfectant. Overheated wire insulation. And fresh blood that had not yet fully oxidized.

Ha Yul stopped. Yu-jin, following close behind, halted at once.

"Why."

Yu-jin's voice was low. Ha Yul lifted her head slightly and spoke forward.

"The smell changed."

It was the odor of a workshop where disinfectant had tried to scrub everything clean, yet beneath it lingered the stubborn reek of blood and fat that refused to be erased. Ha Yul pushed up the wire mesh at the end of the duct. Metal scraped softly. The lock bore clear signs of having been forced open from the inside—more than once. Someone had used this route repeatedly.

Ha Yul pulled herself out first. Yu-jin followed. They emerged into a side space on the upper equipment floor. The ceiling hung low. Pipes twisted in complex tangles. Thick ventilation ducts and electrical cables, along with hastily added wires, snaked messily along the walls. On the floor lay scattered scraps of insulating tape, metal fragments, and drying droplets of blood. This place had been in use. Recently.

In one corner stood what had once been a maintenance room. An iron door blocked the entrance.

"Locked from the outside," Yu-jin observed, studying the handle. Scratches, dents, and impact marks ringed the frame—signs of desperate attempts from within.

"Traces of someone trying to break out from inside as well," Ha Yul said. "Let's open it."

Yu-jin adjusted her grip on her sword hilt and nodded. A short metallic screech followed as the lock was severed. Ha Yul kicked the door inward. It swung open slowly on groaning hinges, releasing a wave of trapped air.

"……Well, this is something."

The maintenance room was not small. Half the original space for managing pipes and air-conditioning equipment had been cleared and repurposed. An old control panel and valves still lined one wall, but the center was dominated by an entirely different structure.

The first thing that caught the eye was the operating table. Unlike standard hospital models, this one sat lower and looked far sturdier, bolted directly to the floor. It featured a space for a torso to lie flat, with frames extending outward to secure arms and legs. Most striking was the apparatus at the head: a neck fixation device. Metal supports were designed to forcibly hold the neck and cervical spine at a precise angle.

The moment Ha Yul saw it, she recalled the black blood crystal fragment they had found inside the neck of the mutant killed below. This was no coincidence. Yu-jin's eyes darkened as she reached the same conclusion.

Fixed belts hung beneath and beside the table—arms, legs, chest, pelvis—meant to pin a body face-up. Layers of dried blood and fluid stained the edges, and long scratch marks from torn fingernails stood out clearly. A disposal bin sat nearby, its lid half-open. Yu-jin's expression hardened as she peered inside. Tangled vascular tissue lay on plastic sheeting alongside thin grayish-white fibers that resembled severed nerve bundles, clumped with coagulated blood. Some fragments looked like partial organs—cut away rather than cleanly extracted, leaving only ragged cross-sections.

The empty corpse from the duct came to mind. Selection had been ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠deliberate. Blood vessels separated from nerves, organ tissue from everything else. Crude, yet systematic. Failures were not simply discarded; usable parts were harvested first.

Three monitors were mounted on the wall. Two were dark. The third flickered weakly, green text barely legible, as though someone had fled without powering it down completely. Connection logs, file lists, and partial experiment records remained frozen on the screen. Yu-jin tapped the keypad beside it. The display brightened slightly. Some characters were corrupted, but the text remained readable.

The blood core. A nucleus that naturally condensed inside a martial artist's body. Whether orthodox or unorthodox, the principle remained unchanged. It was simply the result of a human condensing everything they had built within themselves.

Ha Yul stared at the screen and spoke slowly.

"If the blood core is the condensation of what a human has built, then an artificial blood crystal is nothing more than a nail driven into a person."

The words came naturally, as though she were reading them from the records themselves. It was an insult to every martial artist. The core that a practitioner painstakingly forged through training was being cut apart and hammered in like raw mineral. The result was not stability, but rampage. Humans were not becoming monsters through accident or failure—they were being forcibly turned into monsters by others.

Ha Yul's gaze lingered on CASE 24. Upper floor movement instinct. The final words of the mutant they had killed below resurfaced. Go up. Go higher.

Injected commands, she thought. After blood crystal insertion, the mutants were given specific directionality—pushed upward, guided through particular routes, and directed toward recovery points.

Photos were clipped to the opposite wall. In the dim light they were hard to see at first, but up close they revealed subjects mid-procedure. Ha Yul lifted one. The face was blurred, yet she recognized the subcontractor uniform from the Jongro Redevelopment Area. It matched a photo from the missing persons list.

Yu-jin ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠flipped through several more and exhaled sharply. She rarely displayed anger, but her silence cut deeper than any outburst.

"There are people doing filthy work. And quite systematically. The scale is larger than we thought."

Ha Yul studied the photos again. Same angle. Same position. Artificial blood crystals inserted for the same purpose. Whatever terror or resistance each victim had felt survived only as belt marks. The records noted only success rates and failure causes.

The final entry still glowed on the screen, letters flickering from unstable power.

Both women turned toward the rear of the room. At the very back, where maintenance materials had once been stored, the wire mesh and partitions had been ripped away. Beyond lay a deep rectangular ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠opening in the darkness—an elevator shaft. Only cables and rails remained. The view stretched endlessly both upward and downward. Bloodstains traced a line along the metal rim, as though someone had climbed using their hands. Similar stains and scratch marks continued upward along the rails and walls inside the shaft.

The mutant's dying words, the "upper floor movement instinct" from the records, and the shaft before them aligned perfectly. Ducts, ceilings, maintenance room, shaft—hidden paths for concealment and transport. In a building slated for demolition, the interior was labyrinthine and nighttime security full of gaps. Someone was exploiting those gaps not merely for hiding, but for experiments and movement of subjects.

Yu-jin raised her radio, eyes still fixed on the shaft.

"Send additional personnel upstairs. We have confirmed an illegal experiment facility on the equipment floor. Blood crystal insertion equipment and organ recovery traces discovered. More importantly, there is a high possibility of at least one additional mutant."

A brief acknowledgment crackled back. Ha Yul crouched beside the shaft and touched the rail with her fingertips. The blood was still wet. Something had passed through here only moments ago—human, mutant, or something caught between the two. She could not yet say which, but their next step was clear.

Ha Yul rose. Yu-jin stepped up beside her. Together they gazed into the darkness above the shaft. Nothing was visible. Yet that very absence felt like part of the facility itself.

"Shall we go?" Ha Yul asked quietly.

Yu-jin nodded.

Someone was turning people into monsters. And they were doing it with ruthless, methodical precision.