The Discarded Setting

Getting into the Ancient Ruins had not been easy.

First he had to convince the Academy Chairman and Darius. He told the Chairman it was the perfect moment to raise the Academy's standing. He told Darius it was necessary to lift the Emperor's curse. The reasons were sound enough that both men accepted them.

The problem was the condition attached to bringing Lola.

"We cannot take the young lady of House Lemercier somewhere that dangerous. At the very least, bring the head of the family's permission."

It wasn't wrong, so he couldn't argue. After turning over every possible way to persuade Count Lemercier, he asked Lola to put him through to her father.

Lola, thinking of her father's usual temperament, was sure it wouldn't be a problem. X figured it wouldn't be nearly that simple.

Surprisingly, Lola's father agreed without a fuss.

"A place like the Ancient Ruins could never be a danger to my daughter."

That was his reason. Whether all nobles were like this or House Lemercier was just built different, X had no idea.

And so Lola joined the expedition.

There were two reasons for bringing her. One: she was one of the few 4th-Circle mages at the Academy. The other: to do something about the gloom that had been settling over her more heavily by the day.

"This is the Ancient Ruins…! Commoner — it's the Ancient Ruins!"

Thanks to that, Lola was now swollen with adventurous spirit. The melancholy that usually hung on her had largely burned off. That alone made all the trouble of bringing her worthwhile.

"My lady, let's check the gear first."

X went through the packs he and Lola had brought. Every piece of equipment he'd ordered from Roxwell was accounted for — not a single item missing.

"You've memorized all the names and what they're for, right?"

"Who do you think I am?"

"This stuff is expensive, so try not to lose it."

"Stop treating me like a child!"

Ordering a share for Lola as well had skewed the split to eight-to-two, but he decided to treat it as money well spent. Nothing cost more than a life.

"Everything looks ready. Shall we head in?"

"Good! Escort me properly!"

X and Lola made for the main gate of the Ancient Ruins. The gate alone stood taller than most castle walls. No human strength was going to shove that thing open.

"Can we even open this?"

"Apparently it has never ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠been opened. Not once."

The ground around them was littered with old traces of people — the remains of campsites and fire pits, garbage and waste left to roll in the dirt.

"I heard they were still studying it up until a year ago, then they gave up."

"They spent years and never got past the entrance. Giving up makes sense."

That was how far research into the Ancient Ruins had gotten. Even that much had only been possible because of a hole the Hero party had punched through a hundred years ago.

"I came because you said it was a mission. Do you actually have a way in?"

He had fed Lola a convenient story about a mission from the secret society. Suddenly showing up at the Ancient Ruins and clearing it without a hitch would have looked strange otherwise.

"Headquarters provided the information we need to clear it."

"…Will I get to go to headquarters someday too?"

"Of course you will."

A lie, but still.

He already knew how to open the main gate. He had no intention of using that method. There was no reason to make a spectacle of themselves.

"Let's take the hole at the entrance."

He planned to use the same route Hero Leon had taken in the original story.

"My lady, once we're inside, don't touch anything."

"I know that! But why?"

"If you do it wrong, the structure of the ruins changes."

The layout of the Ancient Ruins shifted constantly depending on certain conditions. Without knowing the exact rules, you could wander for a very long time. The original setting had been modeled on the horror film Cube.

The meaning of that landed, and Lola went pale.

"Then how are we supposed to get out?"

"You can't use ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠magic or artifacts outside, but you can ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠inside. If things go wrong, we'll use this."

"A single-use teleportation artifact?"

"That's right. Ten million El apiece. Be careful with it."

"What? That's cheap for a one-use item."

"…"

He had originally wanted to squeeze Maria for another one, but lately she had been avoiding him with a pitiful kind of dedication. Even a hatchling's suspicion and wrath were not things he wanted to court, so this time he had paid for it himself.

"If we go this way, we reach the hole?"

"Yes."

They arrived at the breach shortly after. A colossal sword-scar was carved into the corner of the gate.

"Who would do something like this?"

"Who knows. Some muscle-brained idiot, probably."

The gap ran all the way through. The door was thicker than a person was tall. That, apparently, was the kind of power Leon had possessed a century ago.

X went in first, checked that it was safe, and helped Lola through. The interior was surprisingly cool, and brighter than expected. The ruins had registered their presence, and the torches had lit themselves.

The moment Lola stepped inside, her face darkened.

"The mana density is thick…"

"…You can tell?"

"It's unpleasant. Like being damp on a night of pouring rain…"

"That's a strangely vivid way of putting it."

Come to think of it, Lola had grown unusually fast relative to her stats. She had started with the magical ability of an average first-year.

And now she's a 4th-Circle mage.

She spent class half-asleep and carried herself like a child most of the time, but Lola was a genuinely capable mage. The 4th-Circle explosion spell she had cast last time without a chant was proof enough of that.

Talent like that, and she's in Class F. Why?

A question for later. For now, they moved forward.

At last they reached the first room. A stone door about the height of a person blocked the way.

"My lady, I need you to follow my instructions exactly."

Lola nodded in tense silence. X fed mana into the stone door. The magic formula carved into it flickered once, and the door opened as if dissolving away.

"As a rule, you throw something in first to check."

He immediately tossed in a spare boot. It hit the floor and tumbled. Nothing happened.

"It's safe. Let's go."

"…What was that, some kind of ritual?"

"Trap check."

He already knew this room was empty. What he was doing now was a performance for Lola. Dumping every secret on her at once would have looked wrong.

Lola tilted her head but followed him in. The moment both of them were inside, the door shut on its own.

"There's not much to this, is there?"

"It's only the first room. Ah — take a look behind you."

"What now… Hegh! The door's gone!"

Lola searched the wall she had just come through from top to bottom. There was no door anywhere on that surface.

"That's how this place is built. You can't go back the way you came. Which is why you have to be careful every time you move forward."

Lola went rigid. Only now did it feel real that they were inside the Ancient Ruins.

There were three ways onward: a stone door in the wall ahead, and one in each wall to either side. He already knew which was safe. He asked her anyway.

"My lady, you choose the direction."

"M-me? Th-then… r-right…"

He knew exactly what that choice led to, and kept his face still. The stone door opened, and reasonably clean air drifted out. On the surface, it looked like nothing was wrong.

"See! I told you! This one's safe!"

"Don't rush."

He caught Lola before she could go ahead and threw the boot. The instant it landed in the center of the room —

KZZZZZT—!!!

Current from every direction incinerated the boot to ash. Lola's face went the color of paper.

"My lady, you just died once."

"I-I want to leave…!!"

"My lady, please calm down. That was a joke."

He barely managed to stop her from activating the teleportation artifact, then continued.

"These ruins have a rule for finding the safe rooms. Once you know it, avoiding the trap rooms is easy."

"…You knew this one was a trap."

"Then I'll explain the rule."

"Hey!!"

X talked over her indignant flailing.

"You need to look carefully at the numbers on the stone doors. There's something like a room number carved on each one. Those numbers are the hint."

Just as he said, a number sat in the center of each door.

"If the number is a prime, it's a trap."

"A prime — a number whose only divisors are one and itself, right?"

That, too, had been lifted from the film that inspired this place. In the original story, the Hero party had wandered the Ancient Ruins for a week. In X's previous life there had been a compass artifact for surveying the safe rooms; this time, it didn't exist. Circe had tried to replicate the compass's magic and failed, so they had ended up wandering without it. They had been on the verge of wiping out from starvation when Circe discovered the prime-number rule and finally cleared the place.

He intended to use that rule now.

"The door in front isn't prime. It's divisible by five. Follow the rule, and that means it's a safe room."

X opened the front door without hesitation. To Lola, the room beyond still looked dangerous.

"Wait — it could still be a trap… Hey, X! Hey!!"

"Don't panic. We don't even need to throw a boot this time."

He walked in as if it were nothing. Lola stared in horror.

"Kyaaah! X, I'm sorry!! If you die I'll at least bury you on our estate…"

"My lady, I am not dead yet."

Sure enough, X was perfectly fine. Lola's eyes went round.

"Why are you alive?"

"…I suppose I just can't seem to die. Anyway, come through quickly. If you take too long the door closes and the layout changes."

"R-right!"

The moment Lola crossed the threshold, the door shut and vanished. Nothing happened on her way to X's side, and the safety of the room finally sank in.

"I-it really is? It's actually safe?"

"We move through the rooms like this. Keep circulating through the sectors until we find Room 1."

"Room 1?"

"That's the final destination."

In the original, Circe had cracked the rule and found Room 1 a day later. X figured they could clear it in about two days.

That's assuming we take the intended route, of course…

"Then let's start the real exploration."

"The real exploration?"

X set down the packs and started pulling things out: long blasting charges, a pickaxe, and a drill. Lola's brow furrowed at the sight of them.

"Bombs, a pickaxe, and a drill…? What are those for?"

"What do you suppose they're for?"

He pointed at the wall where the door had vanished, leaving only blank stone.

"To break something."

It took Lola a second to process that. Then she shrieked.

"What?! Hey! If that goes off in here, we'll all die!!"

The quantity of explosives he had unpacked was considerable. Even in a world that treated gunpowder as an afterthought next to magic, anyone could tell that setting off that much in an enclosed space was a bad idea.

"I don't plan on setting them off in the open. Watch."

He drove the pickaxe into the empty wall first. The stone was brutally hard, but once he wrapped the pickaxe in aura, he could open cracks. He cut a series of them at even intervals.

Lola watched this sudden bout of manual labor with open confusion.

"You're going to break the wall? Looking at how thick those doors were, that's impossible…"

"You're right — a pickaxe alone won't do it. Explosives are another matter."

A charge detonated against a bare surface would only scorch and chip the outside. Stack as many bombs as you liked; that approach was useless.

"So I'm going to drill holes and set them off from the inside."

He took the drill to each crack and bored a deep hole — deep enough that a charge would sit inside with room to spare.

"Now then. Pop quiz: what happens when several identical charges detonate at the same time?"

By then the wall was pocked with dozens of holes, a blasting charge seated in each one. Lola looked at him as if he had lost his mind.

"You're going to spread them out inside the wall and set them all off? That's just wasting perfectly good bombs."

"A waste? Why?"

"Because bombs are only useful if you pile them in one spot and set them off together."

That was the blind spot this world had baked into itself. Magic's existence had left gunpowder neglected — and the techniques for using it had been neglected right along with it.

"Then watch. Come over here, please."

X found a safe door and waited beside it. When Lola came over, he fitted a protective helmet onto her head and dropped to the floor on his stomach.

"We're setting off explosives, so get down like I am."

"What?! You want a count's daughter to do what? And what is ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠this ridiculous helmet…!"

"If something goes wrong you'll get hurt, so on your stomach, please. Put a barrier up around us too… ah, have you learned a sound-dampening spell yet?"

"I have…. Making a noble do this kind of thing…"

Lola grumbled, but she got down and cast the spells. X checked the barrier, then took the detonator in his hand.

Everything was ready. If it went wrong, they could open the door and run. If the ruins started coming down, they could teleport out.

"Firing."

He pressed the detonator without hesitation.

KRAAAAAANG—!!!!!

The instant it triggered, fire and dust erupted from dozens of holes in the far wall all at once. Even with the sound blocked, a massive shockwave rolled through the stone and slammed into X and Lola.

Only after the charges went off did Lola's body lock up on instinct, finally grasping what that kind of force actually meant.

"B-bombs were this strong…"

It was the first time she had seen explosives used in person. She had not imagined those little sticks could do this. X looked at the result in front of him and was reasonably satisfied.

"First time I've tried it by eye. Turned out well."

"F-first time?! You— you—!"

"And that would be the answer to the question I asked you earlier."

The dust of the blast cleared, and the sight it left behind was spectacular. That enormous, impossibly thick wall had split and come down. A wall that would have stood through a barrage of explosion magic had collapsed under a few swings of a pickaxe, a drill, and a few dozen charges.

"The answer is: even a thick wall gets blown to pieces."

"How did you even…"

"That's not important. What matters is what's on the other side of that empty wall."

"Not important, he says…"

As the young lady of a count's house, Lola could not even begin to calculate the ripple effects of what she had just watched. Mining and quarrying in the territory might become several times more efficient overnight. There would no longer be any reason to burn through magic stones just to cut rock.

"What are you…"

X, who did not appear to care about any of that, was already striding toward the collapsed wall to see what lay beyond. He had never been more tense in his life.

Break an empty wall and keep going. That is not how the original story works. In game terms, this is basically a bug.

The core rule of the Ancient Ruins was simple: choose one of three doors and advance. In the original, the Hero party had tried to destroy the walls and gotten nowhere. The walls were that hard, and that thick.

X had brought one down anyway. An empty wall, no less.

If I want to find it, I can't take the orthodox path.

The dust settled, and what it revealed was a room from another space. Three doors — front, left, and right — each marked with a number. X checked the numbers first.

The highest number that appeared in the original was in the nine thousands.

He had run through it several times. Nothing higher than that had ever shown up.

If the number is higher than that…

Front, 5001. Right, 1920. Both lower than nine thousand. Not what he was looking for.

And the number on the left was 969139.

"Found it."

A room from the discarded setting.