A boulder shaped like a horse's head. As we tried to approach it, a fog that hadn't been visible from afar began to shroud the area on all sides.
The fog was so thick that we couldn't even make out the direction we'd come from.
Finally, Sama Yuryeon—who had been waiting for something worthy of her attention rather than trivial matters—stepped forward, positioning herself in front of me and Tang So-wol.
"I've modified the Hwanhwan Mi-jin and the Eunhyeong Unmu-jin, then crammed them together into a single space. …It seems Gwiyeong Sin-tu truly had no intention of hiding the vault in earnest."
"Do you understand something?"
"Yes. Rather than further disorienting the five senses, the formations were attached somewhat crudely—so even if one got lost, a few sijin of wandering would naturally lead them back out."
So the difficulty of finding the way had increased, but it was a formation that allowed one to keep trying again and again.
I thought I understood what Gwiyeong Sin-tu was thinking when he set up this formation.
He must have wanted to see countless martial artists stalled before it, stamping their feet in frustration.
Truly a perverse taste… and yet it never crossed the line—that was exactly the kind of formation Gwiyeong Sin-tu would make.
"Can you find the way?"
"As I said a moment ago, it was made by forcibly merging two other formations to make it more complex, so it will take a bit of time. But…"
"Even if you get lost inside, you can always come back out, so it's fine to act a bit boldly, right?"
Sama Yuryeon nodded at the words Tang So-wol added.
"Once. I think I just need to get lost inside once."
"That much is no problem at all."
Though Sama Yuryeon was the eldest among us, she was still young enough to be called a rising talent.
I knew she wouldn't be able to display the same level of skill she had before the regression. Even so, I'd brought her along because having her was better than not having her at all.
If she could unravel a formation she'd never seen before just by getting lost in it once, that was more than enough.
I nodded and opened my mouth.
"Time to work."
"I've never once slacked off, you know…"
Sama Yuryeon grumbled quietly, then glanced toward me and Tang So-wol.
"Follow only in the exact footsteps I step in."
"Didn't you say we'd get lost at least once anyway?"
"I have no intention of wasting several sijin entirely. Once I figure out the living gate, I plan to head out… but if we're unlucky, some of us might get left behind alone."
"…That would be a problem."
With Tang So-wol's hand firmly in mine, I fell in behind Sama Yuryeon, who shook her head with a slightly disgusted expression.
Then Sama Yuryeon took a step into the mist.
Following her back, I and Tang So-wol also advanced into the mist.
***
Finding the way through the dense fog was more exhausting and grueling than I had expected.
Not physically, but mentally.
The helplessness of not being able to gauge anything pressed down on me harder than I'd thought.
Of course, by the time I was about to feel stifled, I escaped once following Sama Yuryeon, and on the second entry, I was able to break through the formation by following the right path right away.
The sky had cleared as if the fog had never been there at all. Looking back, I could only see the rock shaped like a horse's head, with no trace of the mist left behind.
"It's not my first time going through a formation, but it's fascinating every time."
"Oh? It was my first time, but young hero Cheon has experienced it before."
"…When you put it that way, it sounds a bit strange, doesn't it?"
"How is it strange? I'm afraid I don't quite understand."
"…"
Tang So-wol smiled slyly in front of me as I kept my mouth firmly shut. She pressed her fingertip against the tip of my nose and continued in a coaxing tone.
"Won't you tell me?"
"Whatever I answer, you're just going to use it to tease me again, aren't you."
"Hehe. I suppose I was too obvious. I didn't think I'd be caught so easily."
Still not taking her hand from my nose, Tang So-wol giggled. Only after laughing for a good while did she withdraw her hand and continue speaking.
"Well, strictly speaking, I've seen formations plenty of times myself. In the end, don't the formations that martial artists create also follow the principles of formations?"
"After all, a formation is ultimately about twisting the flow of qi to achieve a desired result. Whether it's by utilizing artifacts and Natural Qi, or by utilizing martial artists and each individual's internal energy."
Several well-trained martial artists moving in a specific pattern, exchanging internal energy to produce greater power—that too is a type of formation.
No, if anything, that could be said to constitute the majority of formations.
Twisting Natural Qi the way we just passed through is only possible in a limited environment, and only for those with superior ability.
Of course, since the range of applications itself differs, one can't simply say one is absolutely better than the other.
Isn't what matters always using the right tool for the right place? Though they are the same type of formation, their uses differ, so it's fair to regard them as different things.
"By the way, I'm a bit curious that young hero Cheon has experienced formations before. You're referring to formations created with such artifacts, correct?"
"Correct. It was an extremely low-level formation, so I just broke through it with raw force."
"Eh…?"
The Demonic Cult enjoys using sorcery, but they don't use formations well. That's because formations aren't of much help in direct combat, and even if one wanted to use them, they require talent and long years of research.
But the Unorthodox Sects are a bit different. Those who use them properly are extremely rare… but there are often cases of people who learned them half-heartedly from somewhere and use them half-heartedly.
In the Orthodox Sects, they know such half-baked formations are meaningless, so aside from the Jegal Clan, they tend to rarely use formations with artifacts.
But the Unorthodox Sects—if it seems like it'll make them even a little stronger, if it can raise their win rate even slightly, they'll try anything, won't they?
"It was quite a while ago. It was when I exterminated the Jeoksa Faction, who were my parents' enemies, and wandered around raiding black-path organizations of similar scale."
"W-wait a moment. That was about four years ago… Could you perhaps be the Blood Flower Sword Demon, young hero?"
Sama Yuryeon, who had been catching her breath with a somewhat tired air from behind, opened her eyes wide.
"Oh? You know of it?"
"Yes. It was fairly well known, after all. If you had kept hunting black-path organizations for about six more months, a bounty would have been placed on your head along with a fitting alias."
"That's exactly why I pulled out early. I had already squeezed out as much money as I could."
And thanks to that, I had obtained the Blood Poison Wine and put it to good use kidnapping Tang So-wol, so wasn't it a profit?
"Come to think of it, four years ago… If the Blood Flower Sword Demon is eighteen now, that would make you fourteen or fifteen at the time… Huh?"
Sama Yuryeon, muttering to herself, tilted her head. I chuckled at her slightly stiffened expression and continued what I had been saying.
"Anyway, in those days, a few black-path sects used shoddy formations. I believe the name was Gwigokmun or something like that."
If I included the time before my regression, there were a few more unorthodox organizations that used formations. Regardless of their scale, the level of their formations was more or less the same.
"My senses grew dizzy, and a bone-chilling Gwigokseong echoed in my ears. But that was all it did, so I just smashed the surroundings a bit and it deactivated on its own."
"Ah, that would be the Gwiyeong Simhon-jin. Normally, if it isn't installed properly, it won't even activate… but the Gwiyeong Simhon-jin has the characteristic that it will activate regardless, just with weakened power. Perhaps that's why it's the formation most favored by swindlers."
Perhaps because the story was something she knew, Sama Yuryeon, who had been flinching on her own, quietly chimed in.
"Swindlers, you say. Well, I suppose that's how it would look to someone properly trained. Speaking of which, how does the Sama Clan teach formations?"
"Teach, you say. I'm not sure if you could call it teaching, but there is a method, at least. After making them memorize the basics of a formation, we drop them right in the middle of it."
"Huh?"
"Most of the time, it's just hallucinations and auditory illusions that aren't life-threatening but are quite frightening… but for a young child, that alone is enough to throw them into a fit."
They repeat this reckless method over and over. In doing so, the child driven into a desperate situation figures out how to break the formation and escape on their own.
Because it's a truly basic formation that even a child can find the exit to, as long as they know the method.
"Your talent for formations is determined by how quickly you escape. Occasionally, there are children who can't get out for over a year. In those cases, they lack talent for formations, so we teach them something else."
"…That's harsh."
Tang So-wol frowned slightly. In response, Sama Yuryeon shrugged with her usual unreadable smile.
"That's just how it is when a family survives for a long time in the Unorthodox Sects. Well! Regardless, you've escaped the formation, so let's hurry and find the entrance to the secret vault! We've walked quite a while, so something should show up soon… Oh? Doesn't that cave look a bit suspicious?"
A blatant change of subject. But there really was a cave a short distance away that looked suspicious at first glance, so everyone's gaze turned toward it.
At a glance, it looked like an ordinary cave, but its location was strange.
No matter how you thought about it, it wasn't a spot where a cave could have formed naturally. As they drew closer, it was practically screaming that it was man-made.
The ground was packed down to make a path. Trees had been pulled out unnaturally, as if to keep them from covering the cave entrance. And there were jagged rocks that had been cut away with tools, not worn by wind and rain.
Still, carving large characters into the upper part of the entrance seemed a bit much.
"So this is the Sin-tu Secret Vault. They made no effort to hide it."
"Well, we did come all the way to a remote mountain foothill in Gansu Province and push through the formation, didn't we? They must have figured there was no more reason to hide it."
Tang So-wol was probably right. Given Gwiyeong Sin-tu's personality, if they had endured this much, it was about time they showed off a little.
I stared into the depths from the entrance for a moment, but it was so deep that only darkness was visible from a certain point onward.
"There doesn't seem to be anything particularly unusual. I'd like to head right in, but… do you need to rest?"
When I asked Sama Yuryeon, who must have been exhausted from getting through the formation, she slowly shook her head.
"No. I rested plenty on the way here, so I'm fine. This time as well, I'll take the lead and check for any mechanism traps…"
"If an unexpected situation arises, we'll step in as well, so don't worry. I may not be good at much else, but I can definitely block arrows and poison."
"Thank you. Then, please follow me."
Sama Yuryeon passed by me and Tang So-wol, walking toward the cave. …Though rather than entering it, she stopped by the wall nearby.
"The entrance is over here, though."
"It's a fake. The real entrance is in front of this."
After looking around the wall here and there, Sama Yuryeon began fiddling with something. And then—
Kugugung-
With the sound of stone scraping, the wall slid backward, revealing a passage leading inward.
"…"
"…"
Since there was no need to hide it, they'd just gone ahead and carved a signboard out in the open—my mouth and Tang So-wol's closed at the same time.
If we'd come alone, we would've wandered around here for a long while longer.
As expected, having an expert really does help.
Whether she knew how embarrassed we felt… no, she definitely knew and was pretending not to.
A small night pearl was embedded in the wall, and standing before the relatively bright passage, Sama Yuryeon urged us on.
"I can't go in alone—I'm too scared."
"I'm going now."
"No, but why is Grandpa's spring painting showing up in a place like this…?"
"Better than having the Sama Clan's secret art stolen."
I shrugged at Sama Yuryeon, who was wearing a rare look of bewilderment.
It didn't seem to comfort her much.