Experiment (1): The Body's Lie
After the meeting ended, the sound of chairs scraping and file folders snapping shut began to overlap one by one, loosening the heavy atmosphere that had filled the conference room with words like national-level incidents, artificial Guiin, and the infiltration plan for Yongsan Military Base. Ha Yul rose from her seat. It was her first meeting since returning, and though her body was clearly much better than before, a dull ache still lingered somewhere deep inside. That pain was proof she had survived, and at the same time a warning that pushing herself too hard could make things worse again.
Stepping into the corridor, footsteps soon followed from behind and naturally fell into step beside her. It was Yu-jin. She matched Ha Yul's stride for a few steps, and in the brief silence that settled, she spoke in the most neutral tone she could manage, as if simply delivering a newly realized concern.
"Ha Yul, I want to ask you something seriously. Have you ever thought about properly learning how to handle Blood Qi? Your methods have worked so far—especially against monsters. Your combat sense for tearing arteries, shattering joints, and turning regeneration against the enemy already surpasses the top tier."
Her words came faster than expected, so Yu-jin paused to steady her breathing.
"But the enemies we'll face from now on are different. It won't just be mutants with Blood Crystals implanted. We'll see more human-shaped experimental subjects like Blood Crystal Martial Artists. At that point, simply using your body well might not be enough. You already felt it once in the Jongno underground, didn't you? Even if the methods for hunting monsters and fighting martial artists overlap in places, they can't remain on the same line all the way to the end."
She could have stopped there. Logically, it was already sufficient. Yet Yu-jin couldn't bring herself to stop. The more she spoke, the more the feelings she had tried to hide seeped through.
"Of course, I know your sect's circumstances and why you insist on external arts. I have no intention of meddling recklessly. But honestly, I keep picturing you getting hurt again and being carried out. Last time you were lucky to make it out alive. That luck won't last forever. I know it might bother you that I'm interfering with your fighting style, but I still felt I had to say it. Even if it's not deep Blood Qi manipulation, just learning basic control and physical reinforcement would change your options. I could teach you myself, and we wouldn't need to drag it out—we could adjust it to fit your style. So this is a suggestion as team leader, but…"
Her words trailed off. She knew herself that saying more would make her feelings too obvious. Ha Yul glanced at Yu-jin's profile faintly reflected in the corridor window. She had tried to present it as a calm, rational proposal, yet the lengthening explanations, the extra step beyond what was necessary, and the natural assumption that "I could teach you myself" all revealed her intent. Ha Yul found it rather endearing. This wasn't someone who usually spoke in circles, but once emotion got involved, she tried to hide behind logic.
After a few more steps, Ha Yul replied in a polite, steady tone.
"I appreciate the suggestion. I know you're saying it out of concern for me. But I don't think it will work. I'm the successor of the Hyeol-a Sect. We haven't even found the next heir to carry on the line, so if I abandon the principles first, it would be the same as erasing the sect with my own hands."
It was a perfectly legitimate reason. It was also true. Yet the real reason lay deeper still. Ha Yul didn't voice it. She knew it herself. Unlike other martial artists, her problem wasn't with her body. The heat was annoying, but the real issue was her mind. As Seol-hwa had said, her body was too quiet. No signs of mutation, no toxic reactions, no traces of excessive awakening. If a body like that began properly handling Blood Qi, nothing might show on the surface, but it could collapse from the inside.
Without revealing that true reason, Ha Yul finished.
"And honestly, learning a new path now would take too much time. It might not even suit the Hyeol-a Sect's martial arts. I doubt the previous successors clung to external arts just for show. I have the method I've maintained until now, so it would be better to find a way to grow stronger without abandoning it."
A trace of disappointment crossed Yu-jin's face. It might have been the answer she expected, or the one she had hoped wouldn't come. She didn't press further. Instead, Ha Yul read the look in her eyes and took a step closer to comfort her.
"More than anything, we'll keep fighting together. I have no intention of stubbornly trying to handle everything alone. I'll rely on you often, and if I need to, I'll say so first. I rely on you more than you think, Yu-jin. So don't look so disappointed."
It wasn't the acceptance Yu-jin had wanted, but it was a consolation that eased her feelings in its own way. Especially the part about "I'll rely on you often" landed better than any persuasion. Yu-jin gave an awkward cough and turned her gaze away a little faster than usual.
"Who said I looked disappointed? Anyway, I got it. If you're that firm about it, I won't force the issue. But if you throw yourself into danger and overdo it again next time, that suggestion might turn into an order. Be ready for that."
Ha Yul lifted the corner of her mouth just slightly, as if holding back a laugh.
"Yes, Team Leader."
Yu-jin seemed worried that staying any longer would let her emotions show on her face, so she turned and walked away at a speed that wasn't quite awkward.
"Look at those light steps. The team leader really is cute."
As Ha Yul watched her retreating back, a light laugh sounded beside her. It was Dang Seol-hwa. She had appeared at Ha Yul's side so naturally that Ha Yul hadn't noticed when she arrived, and she was now watching Yu-jin's departing figure with interest.
Ha Yul turned her head slightly toward Seol-hwa and asked, "What business do you have?"
Seol-hwa didn't bother with roundabout words.
"I was wondering if you're interested in poison instead of Blood Qi. I didn't catch the whole conversation, but I got the general flow. In the end, the point is the same. With your current strength, the enemies you'll face might be too much. Whether it's Blood Qi or poison, the difference is only in direction and degree. Both change the body to push past its limits."
Ha Yul answered immediately. "I insist on cold weapons."
Seol-hwa's lips curved upward as if she'd been waiting for that.
"Don't snakes and spiders use venomous fangs when they hunt? Using poison doesn't suddenly make them not hunters. It might even make them smarter predators."
There was no easy rebuttal to that logic. Ha Yul closed her mouth, then finally let out a sigh. Seol-hwa didn't miss the opening.
"Either way, it's true that you're feeling your limits in your current state. You learned that the hard way in the Jongno underground, and you might have to pay an even steeper price from now on. If Blood Qi mutation feels off-putting, shouldn't you at least test using poison? I'm not telling you to live like a true Dang Clan successor. I just mean, what if you try deceiving your body in a different way?"
Seol-hwa's suggestion was dangerous and dubious, yet strangely persuasive—too much so to dismiss lightly. More than anything, Ha Yul herself had already admitted during her talk with Yu-jin that things would only get harder from here. Especially when she thought about Blood Crystal Martial Artists and what might come after.
After a moment's thought, Ha Yul turned her gaze toward Seol-hwa.
"Where do I need to go?"
Seol-hwa smiled in satisfaction.
"I like how quick you are. The Murim Agency Cooperative Research Institute. I have a lab reserved there for a bit."
The two of them immediately changed direction toward the research institute. As they moved from the corridor to the elevator, then through the underground passage into the experimental zone, Seol-hwa simply hummed to herself without further explanation.
The small laboratory inside the institute was much smaller than the previous dissection room, and all the more gloomy for it. It looked like the perfect place to sit someone down and inject or observe something. While putting on gloves, Seol-hwa spoke casually.
"We have some time until the infiltration of Yongsan Military Base, but learning the Dang Clan's methods properly in that window is impossible."
Seol-hwa opened a refrigerated storage unit and took out a small vial and syringe, smiling playfully.
"To use poison arts the Dang Clan's way, you have to train your body from childhood with great consistency. Accumulating poison in your blood, circulating it like Blood Qi, making your body accept it as part of itself—that isn't something that happens in a day or two."
She slowly drew the liquid from the vial with the syringe. It was nearly colorless, but under the fluorescent lights it carried a faint golden sheen. Seol-hwa held the syringe up to the light and continued.
"Every substance in this world is poison. Nothing exists that isn't poison. Only the precise amount separates medicine from toxin. Who controls that boundary, and how precisely—that's how we distinguish the level of someone who has mastered poison arts."
She wiggled the syringe as she spoke.
"Strictly speaking, this is closer to a steroid-based amplifier. But unlike ordinary muscle enhancers, the difference is that it tricks your body into believing it has no choice but to grow stronger."
Ha Yul narrowed her eyes slightly.
"Even so, it's just doping that only works for a short while, isn't it?"
Seol-hwa shook her head.
"The human brain doesn't objectively analyze its surroundings. It always prioritizes information that benefits itself, is efficient, and aids survival. We usually call that bias, but biologically it's also a remarkably clever form of self-deception. This drug doesn't directly command the muscles to 'get stronger.' It whispers to the brain, 'This body can already produce greater output.' If the brain believes it, the suppressed limits of the body loosen, and the body begins to actually restructure itself to match—even if only for a very short time, or only in certain conditions."
Listening to the explanation, Ha Yul grew more uneasy.
"That's far too convenient. If something like that were really possible, everyone would already be using it."
Seol-hwa pushed out a small air bubble from the tip of the syringe.
"Yes. Not everyone can use it. Because it breaks either the body, the mind, or both. That's why I can't recommend it to just anyone."
Ha Yul asked at once, "What are the exact side effects?"
Seol-hwa answered in a calm tone, but the content was far from reassuring.
"Physically: heart attack, myocardial infarction. Blood pressure rises, heart rate amplifies abnormally, and when it exceeds the limit, that's what happens. Mentally: emotional instability, increased impulsivity, sensory hypersensitivity, heightened aggression. The body tries to grow stronger like mad, but the mind can't keep up, so it can split apart. But given that you've never shown any physical mutation symptoms despite insisting on external arts, the physical side probably isn't something you need to worry about too much. Your body is strangely quiet, after all."
Ha Yul spoke immediately. "The mental side isn't exactly easy either."
Seol-hwa shrugged as if it were nothing.
"If a problem arises, I'll just sedate you right away with paralytic and sleeping poisons. All I have to do is lay you down before your heart stops and put you to sleep before you go berserk."
The way she so casually referred to forcibly knocking someone unconscious as "sedation" was very much like Seol-hwa. Ha Yul almost laughed in disbelief, yet at the same time she found herself persuaded. They had the necessary equipment, Seol-hwa was an expert in poisons, and her body didn't follow ordinary standards. In that case, testing it now might be better than having it erupt on the battlefield later.
Seol-hwa stood before Ha Yul with the syringe in hand.
"The choice is yours. It's impossible to become dramatically stronger in just a few days before entering Yongsan. But at least you'll be better off than you are now. And that improvement will shine even more in actual combat."
Ha Yul slowly leaned back in the chair and rolled up her sleeve, exposing her arm. After the Jongno underground, she had already finished denying her own limits. If she encountered something like a Blood Crystal Martial Artist again, she might not be able to endure it next time. She had rejected Yu-jin's method, but that didn't mean she could do nothing and stay as she was. Meeting Seol-hwa's eyes, she said, "Let's try it. But if I really start going berserk, then do exactly as you said and knock me out right away."
Seol-hwa's eyes curved into thin crescents.
"Of course. The core of this experiment is seeing how far you can go before you truly break."
A cold alcohol swab wiped across the skin of her arm. Seol-hwa confirmed the vein location, then brought the needle over with practiced ease. The brief sting as the syringe tip pierced the skin, followed by the sensation of cold, viscous liquid entering along the blood vessel. Ha Yul unconsciously let out a long breath.
"Hoo…"
Seol-hwa glanced at her wristwatch while adjusting the injection speed.
"Good. From now on, your body might react first, or your mind might become sensitive first. If your heart rate rises, you can tell me. Even if you don't want to speak, it will show in your eyes, so there's no need to hold it in."
The liquid inside the syringe slowly decreased. There was still no major change. The air in the lab, the low electronic hum of the machines, Seol-hwa's gloved hands, the reflected light on the metal tray—everything remained the same. Yet that very stillness only heightened the sense of foreboding. Ha Yul felt a faint ripple spreading somewhere deep inside her body. It was like a door quietly unlocking from within.
And Seol-hwa, her face expectant of that change, calmly turned on the monitor.
The experiment had begun.