With a loud bang, the door swung open.
Three figures stepped into the room.
Yuki looked up from the documents he had been reading.
"Hey, welcome back."
He called out to the three.
But— "Yuki, that was impossible. The hidden zone was brutally hard."
"Yeah, up to floor 50 it was smooth sailing.
But past floor 55, Death Knights started patrolling in squads.
With that kind of force, it'd be way too tough for regular soldier-class fighters.
The real problem was from floor 59 onward, though."
"That was insane."
The three launched into animated conversation. They were fired up, apparently, showing no regard for their listener.
A glance at their clothing told the story—chain mail was shredded and broken in multiple places. No one would doubt it had been a fierce battle.
The three carried on.
"The boss on that floor spawned Death Knight Captains — Death Knight Commanders — three of them at once!
And each one brought along five Death Knights under their command!"
"That was brutal… They probably lured us into a false sense of security by going easy on us up to floor 50."
"The bull-headed demon that seemed like the real boss on that floor was A-rank equivalent too."
"In any case, with that many powerful demons guarding the place, there's definitely something hidden in that labyrinth."
"Oh? So you three gave up on floor 59?"
"Well, we managed to take out all three sets of Death Knights and the captains.
But…"
"The guardian—some kind of boss with that title—on floor 60 was absurdly strong."
"Going into floor 60, we were bracing for a war of attrition since we were almost overwhelmed by numbers on floor 59…"
"In the end, we were defeated by a single humanoid demon."
"Calling it an upgraded Death Knight wouldn't even begin to cover it. The strength was clearly abnormal."
"That one—impossible. No matter how many times we tried, we'd lose."
The three settled into their chairs after saying their piece, having calmed down somewhat.
They sipped the tea that had been served and caught their breath.
Yuki, thinking to himself that his predictions had been largely correct, posed a question to the exhausted trio.
"So there was definitely something beyond that, huh?"
Apparently, the three had left the city immediately after being defeated on floor 60. They linked up with
Their reasoning: they feared pursuit.
Before their challenge, the record had been floor 39, with adventurers stalling out at the boss guarding floor 40.
Yet they had surged past that in one go—making themselves highly conspicuous.
Once they confirmed that a guardian of overwhelming power guarded the levels beyond, they realized the mission had failed and retreated.
After a brief deliberation, the three shared their conclusions: "There's no doubt. There has to be some kind of facility beyond that floor."
"The labyrinth was enormous. I think it's been expanded through magic, but it's not a constructed structure. There weren't any underground ruins at that location originally. So an expansive space being carved out there wouldn't be strange."
"That floor had abnormally heavy defenses. Whatever they're guarding, it's something important. Not just the knight that beat us—behind it there were skeletal mages and a death dragon. Compared to any other floor, the fighting force was off the charts."
"Right.
It sounds laughable, but…
I'd say if every demon from floors 1 through 50 fought the demons on floor 60— The floor 60 bunch would win."
Shinji and Shin nodded in agreement with Mark's assessment.
That was the overwhelming pressure they had felt.
Floors 1 through 50 were the original labyrinth, designed to attract visitors, while floors 51 through 60 served as the defensive perimeter. That much seemed certain.
After a light meal and a chance to settle down, Yuki listened to a more detailed report.
They hadn't been able to enter the Demon Country proper, but they had gathered intelligence from the easygoing adventurers in the Labyrinth City.
He had them compile everything into a report.
Various acquisitions and spoils of war.
High-quality "magic crystals" could be obtained from demons.
Each item was Rare Grade , and the bardiche Mark had obtained was Unique Grade .
Whoever had set this up had invested staggering amounts of gold and effort to construct these mechanisms and draw people in.
One piece of information particularly caught their attention.
Apparently, on a certain floor of the Underground Labyrinth , there was a city.
"So it's as I thought."
"Yeah. I'm sure of it."
"Right."
"The problem is, we can't break through floor 60."
At the very least, with only Shinji's group, it was absolutely impossible. Shinji reported this bluntly.
There was no point in putting on airs—the boss had been far too strong.
"By the way, how would you rank that boss's strength? Can you compare it concretely to anyone in the Imperial Guard?"
Yuki's question set the three thinking.
Though they served in the Imperial Guard, there were people like Shinji's group who had no interest in the rank-competition battles within the corps.
Yuki had helped them out with various things since they'd arrived in this world, so they followed him and assisted accordingly…
But since they had zero interest in the top 100, they'd never seriously participated in any rank-competition battle.
When the Corps Commander had been replaced by Yuki, they had transferred from their original Armored Corps to Yuki's mixed corps specifically because they wouldn't be forced into pointless competition there.
There were a number of "Otherworlders" who shared this mindset—people who lived comfortably, avoiding the spotlight, making sure no great responsibility landed on their shoulders.
Since the true strength of these people was unclear, whether the Imperial Guard was truly the strongest group remained a mystery…
But nominally, there was no denying this group was the Empire's mightiest.
"Let's see… At least within the top 50…?
The lower-ranked ones wouldn't even be worth mentioning."
"That's per individual knight, right? We had all three of us attacking and couldn't even touch the thing?"
"Right. Maybe people in the top 30 could fight a knight on equal footing?"
"Now that you mention it… There was a deployment a while back to slay a Greater Demon General , wasn't there? I participated as a military physician…"
"Oh, the 'Lakeside Drenched in Crimson' incident? Seriously, you survived that, Shinji?"
"…I'm glad you made it out alive."
The "Lakeside Drenched in Crimson" incident was one of the most abhorrent events in Imperial history.
A vassal state bordering a beautiful lake had turned against the Empire, declaring independence. The king, severely outmatched in military strength, resorted to a desperate measure.
A forbidden secret art—demon summoning.
The king commanded the summoning of the most powerful demon possible, and the court wizard complied.
In a small kingdom with fewer than ten thousand people, there was no chance of victory against the Empire— But the king had his reasons for declaring independence.
The Empire's nobility had demanded his only daughter, the princess.
Within the vast Empire, it was impossible for the Emperor to personally monitor the movements of every small state.
It was a common sight for provincial margraves, entrusted with local governance, to wield the Emperor's authority and carry out atrocities.
As a result, the small kingdom was destroyed by the Greater Demon General that emerged from the summoning.
The demon's desire was the kingdom's princess.
The court wizard's mind shattered the instant he laid eyes on the demon, and driven insane, he offered the princess up to satisfy the demon's demand.
The demon wore an evil grin and possessed the princess's body.
It achieved incarnation.
The king was consumed by fury. But that fury was quickly replaced by terror.
The demon had gone berserk.
Ultimately, the destruction of the small kingdom reached the Empire, and the decision was made to subjugate the demon.
If the response had been any slower, a second
The once-beautiful lake had been stained crimson with the blood of the kingdom's inhabitants.
It was deemed the worst atrocity in centuries of Imperial history.
"Well, yeah. But here's the thing.
From what I saw during the fight, the Greater Demon General and the floor 60 boss—I felt they were on the same level."
"Huh? A Greater Demon General isn't something we could hope to beat!"
"…Are you really sure they were that close?"
The "Lakeside Drenched in Crimson" incident had been resolved by the Armored Corps, which maintained branches across the Empire.
That was the official story.
But Shinji, who had been deployed with the army, had watched from a distance as a handful of soldiers defeated a Greater Demon General that the main force couldn't scratch.
He had no intention of saying it out loud, but he believed those soldiers were most likely the ones now serving in the Imperial Guard.
That was precisely why he had lost all interest in rank-competition battles.
He had experienced firsthand that they lived in a different world.
"Yeah, they were probably about the same. I wish we had a device that could measure their power, but it probably wouldn't matter much. The knight seemed to be a high-level swordsman, and the skeletal mage behind it had an aura of Intimidation on par with a Greater Demon General ."
Shinji's words were firm and full of conviction.
"Well, then there's no shame in us losing. Two of those things plus a dragon behind them? That's way too harsh. The balance in that labyrinth is completely broken."
"Up to floor 50, the balance was pretty reasonable…
So the hidden zone really is the key. There has to be a city beyond that floor."
Receiving their report, Yuki deliberated.
He couldn't judge precisely without seeing it with his own eyes, but it appeared that a floor was guarded by what amounted to two Greater Demon General -class entities and an undead dragon.
The research facility they were after couldn't be reached without getting past that.
(Man, nothing's ever straightforward, is it?)
If Yuki went to the labyrinth himself, breaking through would be easy enough—but Rimuru's group would notice immediately.
The reason they hadn't intervened in the labyrinth was precisely because they were keeping tabs on Yuki's movements.
Still, he wanted to establish some means of conquering the labyrinth. He could ignore it, but he had a nagging feeling that problems would arise down the line.
Yuki pondered for a while, then spoke.
"Thanks. Take it easy and get some rest.
Oh, and if you want a closer look at the equipment you brought back, you should visit Court Wizard Gadril.
Shinji, you should go pay your respects to your old master while you're at it.
Also, the Materials Division will buy anything you don't need, so feel free to sell your extras."
He commended the three and gave them those parting words.
His words reminding them of their fatigue, the three looked relieved, expressed their gratitude to Yuki, and exited the room.
The seeds had been planted.
This information would spread to other departments quickly.
The Empire would make its move.
Yuki considered this and allowed a faint smile to cross his face.
— The three left Yuki's room and went to the Materials Division to sell their "magic crystals" and unwanted equipment.
Though the reconnaissance mission had ultimately failed, they had earned a considerable income in a short period.
Military pay was above average for civilians, but not enough to live luxuriously. And as for leaving the army and striking out on their own—conditions in this world were harsh.
The stability alone was appealing.
"Hey, where did you get this 'magic crystal'? You don't see quality this high very often these days!"
"This equipment's top-notch too. Pure
"Haha, where we got them is a secret. Don't ask again."
After that exchange, each of them retired to their rooms for the rest of the day.
They had been on a forced march—both body and mind must have been utterly spent. Shinji didn't wake up until the following evening.
Once he was awake, Shinji reached out to the other two.
Shin was already up, but Mark was still asleep.
In truth, Mark had been the most active of the three during the mission, so his fatigue was likely the heaviest.
The three arranged to meet up and went to dinner.
They chose a high-end restaurant in the Imperial capital—among the finer establishments in the city.
This kind of luxury had been a long time coming.
What made it even sweeter was that Yuki hadn't asked for any of their spoils and let them keep everything.
During military operations, war spoils belonged to the military unless a plunder permit had been issued.
In this case, they could have lost everything without being able to complain.
But most of all— "If they tried to take all the money we earned too, I'd seriously think about immigrating for real."
When Shinji made that remark, the other two agreed.
One gold coin was worth roughly 100,000 yen.
This exchange rate held true across the Empire as well.
Gold coins minted by the Dwarf Kingdom were the standard, their quality uniform as official currency.
Some regions issued their own gold coins, but money changers applied strict scrutiny and charged hefty fees.
As a result, Dwarf Kingdom-minted gold coins dominated all transactions.
Dwarf Kingdom gold coins had enchantments baked in—counterfeits were detected immediately. If anyone was caught forging them, it meant death.
The current reality was that very few fools attempted to counterfeit currency.
The gold coins Shinji's group had acquired in the Labyrinth City—the satellite city of the Demon Country—were unmistakably Dwarf Kingdom-minted.
They could be used in the Empire without any issues whatsoever.
Military personnel were paid on an annual salary basis, including raises for promotions, calculated and disbursed in a lump sum.
However, provisions existed for those without savings—the moment one enlisted, a daily-disbursed stipend was provided.
For a common soldier, it was 10 gold coins—equivalent to an annual salary of 1 million yen.
Since housing, food, and clothing were covered by the military, this was a significant sum for those of modest means.
The total gold coins they had earned exceeded one hundred.
Mark and Shin held the rank of Lieutenant.
Shinji, holding a military physician qualification, was a Major—two ranks higher, though without command authority.
Otherworlders received preferential treatment, so the minimum rank assigned was Second Lieutenant.
Naturally, their annual Imperial pay was substantially higher than that of common soldiers.
But even so, it was only around 50 to 100 gold coins per year.
This short-term mission had earned them more than their entire annual salary.
And beyond that— Unique Grade equipment was the kind of thing they would never come into contact with unless it was specifically issued to them.
The primary reason Mark despised Damrada was his ostentatious wealth—it rubbed him the wrong way.
It was jealousy, plain and simple, but in a sense unavoidable.
While they were serving as the military's dogs, Damrada was living it up doing who-knows-what—and that gnawed at him.
Moreover, he grew disgusted with himself for thinking such things, which only made him lash out at Damrada even harder.
Shinji understood Mark's feelings, but since he himself was only collecting a military physician's stipend, he kept quiet and defused the situation whenever he could.
Speaking carelessly would only further sour Mark's mood.
This was what the three of them thought about, based on the intelligence they had gathered during this mission: They didn't necessarily have to cling to the military.
The three of them could simply settle down in Labyrinth City.
The Empire was indeed at the forefront of culture and technology—a magnificent capital.
The food was delicious, and living was comfortable.
With money, they could enjoy a life at least as fulfilling as in their original world.
But they were still military.
Dangerous missions could be assigned at any time, and they could never let their guard down.
The Underground Labyrinth , on the other hand, had everything they could ask for.
There was no risk of death.
They had been skeptical at first, but having experienced it firsthand, they had no choice but to believe.
If there was no danger of dying, wouldn't it be better to live comfortably and enjoyably there?
Such thinking was entirely natural.
Money alone was meaningless without entertainment…
But the labyrinth city had a place called the arena, which was freely accessible on holidays.
It hosted various games and sports—soccer, baseball, and more—and the citizen-adventurers enjoyed them regularly. They had already confirmed this.
As for food quality, it was on par.
Not just on par, but it even recreated nostalgic flavors and items that didn't exist in this world, drawing in their hearts as Earth natives.
Frankly, the only thing tying them to Yuki was a sense of obligation—they had no strong desire to betray him.
If war broke out, deserting would make them enemies on the front lines. Fortunately, this was peacetime.
Now was the time to retire from the military.
"The problem is… war."
Mark murmured.
The reason they couldn't commit to a decision.
It came down to what he had just said.
War would certainly begin. Otherwise, they would have left the Empire long ago and relocated to the Labyrinth City.
"Who do you think would win?"
"Or rather, what if we were ordered to attack that city? What would we do?"
The three exchanged glances.
In more ways than one, that was something they desperately wanted to avoid.
Part of it was that they had grown fond of the city after just a short stay. But considering the strength of the labyrinth's bosses, they could only imagine that the strongest fighters of the Demon Country were beyond anything they could fathom.
"Common sense says that a guardian protecting an important facility being strong is natural, right? But the military of that country is made up of demons too. If that's the case, that guardian probably isn't the strongest they've got."
"I think so too. At the very least, Demon Lord Rimuru is in a different league entirely. Apparently, in the past, an evil dragon called Veldora or something caused an entire city to vanish…
Something similar could genuinely happen."
"A Greater Demon General is equivalent to what we'd call a tactical nuclear weapon back on Earth."
"Right. Wars are about numbers, but throwing numbers at that boss would be pointless."
"It'd take dozens of people at our level to have any chance."
The three talked late into the night but couldn't reach a firm conclusion.
In the end, the only decision they made was to leave the military before the war started, and they parted ways for the evening.
— In an executive office furnished with an opulent desk, a one-eyed man sat in a high-backed chair.
A gaunt man in his forties, his left eye hidden behind an eyepatch.
His name was Caligurio.
He was the Corps Commander of the Armored Corps—the largest faction within the Empire.
On the desk before him lay several "magic crystals."
They were high-purity, high-quality "magic crystals"—the source of magical energy.
In his hand, he held a sword.
Forged from high-grade Magisteel, its craftsmanship was clearly of a superior standard.
A magnificent blade, rivaling the finest work of the Dwarf Kingdom's master smiths.
He was told it had been purchased by the Materials Division, but it stood head and shoulders above anything circulating within the Empire.
A contact among high-ranking nobles whom Caligurio was close with had also reached out to the Materials Division, requesting that any notable items be reported to him.
As usual, this time was no different.
The noble friends he had cultivated showed up in force, grinning unpleasantly as they delivered their report.
Caligurio had risen from minor nobility—without his military position, these high-ranking nobles wouldn't have given him the time of day.
They looked down on him, but they knew the proper etiquette toward the commander of the Empire's largest faction.
Their relationship was therefore one of mutual respect.
According to them, harvesting "magic crystals" of this purity from naturally occurring demons was impossible.
If a stable supply was the goal, they should secure the location producing these "magic crystals"! That was their proposal, framed as a report.
High-ranking nobles never moved without considering their own interests.
There was no such thing as a report given out of pure goodwill.
They had also mentioned another matter of interest.
That was the sword in Caligurio's hand.
Apparently, they had claimed it was "a rare item with a mysterious effect" and urged him to buy it, saying it could contribute to strengthening the Imperial military.
In the end, they had pushed it on him for 100 gold coins. But Caligurio did have his own reasons for being intrigued.
The hole drilled through the blade.
Did it serve some purpose?
Caligurio couldn't determine its significance on his own.
So after deliberation, he sent it to the technical division.
He figured they would make some kind of discovery.
A few days later, when the results were brought to Caligurio, he was struck with both astonishment and resolve.
He realized the sword had been crafted using techniques rivaling their own finest work.
And when he learned its origin—an Underground Labyrinth belonging to a certain nation—Caligurio began formulating a plan in his mind.
A thin smile crossed his lips as he thought: The time has come. I cannot allow anyone to get ahead of me.
He felt a twinge of pity for his colleague—who, despite having the chance to obtain this critical information, had failed to recognize its value and let it slip away.
After all, that man was nothing more than a fool who had risen above his station.
Mocking his colleague, Caligurio's mind never stopped working.
How could he position himself to reap the greatest benefit?
Deep in thought, he considered the opportunity to request a military operation from the Emperor.
It was Caligurio's actions that would set the Empire into motion.
A note, though it probably doesn't need saying: If
Facing three opponents simultaneously alone, he would certainly lose.