Rimuru stared at the two types of crystals Ren had produced, his expression turning serious.
"So pure…" he murmured.
"These magicule crystals are incredibly refined. Even in places with extremely dense magical energy, something like this would be rare. How did you manage to obtain so many?"
As he spoke, Rimuru had already activated his Ultimate Skill—Wisdom King—to analyze them.
The results left him genuinely shocked.
According to Wisdom King's assessment, the energy contained within these crystals was even denser than the magic crystals that once formed naturally in Veldora's cave.
Even more astonishing—
The magicules inside were completely free of impurities.
That meant someone could absorb the power directly without suffering any negative effects from foreign magical energy.
"Just think of these crystals as something produced by one of my skills," Ren replied casually.
"There are two types."
He held up a purple crystal first.
"This one is called a Demonic Energy Crystal. It's suitable for monsters and magic-born races."
Then he lifted a blue one.
"And this one is a Spirit Energy Crystal. Humans—like adventurers—can safely use it."
"As for the effect… both types basically do the same thing."
"They can directly increase a user's strength or rapidly restore the magicules inside their body."
Rimuru—being an otherworlder like Ren—didn't react too dramatically.
But the others standing nearby, especially Milim, immediately showed clear shock.
They picked up the crystals from the ground and examined them carefully.
Unlike Rimuru, who had essentially been blessed with a protagonist-level cheat ability that let him grow stronger as easily as drinking water, beings like Veldora and the others knew something very well.
For monsters, rapidly increasing their strength was not easy.
Normally, monsters had only two ways to surpass their limits and grow dramatically stronger in a short time.
The first method was obtaining the Seed of a Demon Lord, breaking through the limits of their species.
The second was receiving a name from a high-level monster or magic-born. Once a creature became a Named Monster, their magicule capacity could increase rapidly.
But both of these methods shared a common problem.
Not only were they incredibly difficult—
They also generally happened only once in a monster's lifetime.
And yet the crystals Ren had just produced?
He was claiming they could also make monsters stronger in a short period of time.
Without side effects.
Without restrictions.
That was practically equivalent to a legendary treasure.
"Well, it's not completely without limits," Ren added with a shrug.
"For beings at our level, these crystals won't really increase our strength anymore."
"At best, they're just a quick way to restore magicules."
"But since we're trying to create the feeling of a real RPG game, right?"
"In games, you grow stronger by defeating enemies and gaining experience."
"So we can scatter these crystals throughout the labyrinth according to their grade."
"Think of them as experience points."
"Place them in different corners of the dungeon, and it should work perfectly."
Ren paused before adding another idea.
"And at the entrance of the labyrinth, it would be best if the dwarves forged a magic stone monument."
"It could display a ranking list showing how far challengers have progressed."
"That way, it'll attract famous adventurers while also fueling their competitive instincts."
"After all, no player who enjoys games wants to settle for anything less than being the strongest."
As soon as Ren finished speaking, Rimuru's eyes lit up.
He nodded enthusiastically.
The more he thought about it, the more convinced he became that inviting Ren to join this project had been the right decision.
Ren's suggestions were incredibly practical—far more reliable than anything Milim or the others had come up with.
"So," Ren continued thoughtfully, "the reason you originally asked me to participate…"
"…was probably because you wanted to use my identity as the King of Falmuth to help human nations gradually accept the existence of this dungeon, right?"
Among the allied nations of the Tempest Federation, only two human kingdoms existed—Falmuth and Blumund.
But Blumund's population was too small to have much promotional influence.
That was why Rimuru had sought Ren's help.
"Since that's the case," Ren said, smiling slightly, "why not go all-in on the RPG concept?"
"We could also change the promotional strategy."
"Because of the growing trade between our nations, more merchants are traveling between countries now, right?"
"We can use those merchants to spread rumors about the dungeon."
"We'll say that only true 'strong individuals' have the right to challenge it."
"And the qualification to challenge the dungeon…"
"…will be hidden randomly among the goods we sell."
"Only those who possess both strength and good fortune—those chosen by fate—will receive the qualification."
"If we do that, the dungeon will gain a powerful mystique."
"And at the same time, it should boost the sales of our products."
After Ren finished his long explanation—
Milim and Ramiris were both staring at him with blank expressions.
Their heads were practically filled with question marks.
They had understood almost nothing.
But somehow…
It still sounded incredibly impressive.
Rimuru, on the other hand, was getting more and more excited the longer Ren spoke.
At one point, he even began suspecting that before being reincarnated into this world…
Ren must have been some kind of ruthless business tycoon.
After all, when he himself had been just an ordinary office worker on Earth, none of these ideas had ever crossed his mind.
But Ren?
He was manipulating human vanity and greed with surgical precision.
If anyone deserved the title of true Demon Lord, it was probably him.
Compared to that, demon lords like Ramiris almost looked like jokes.
Of course, Ren's insight into human nature wasn't accidental.
After all, he had once served as one of the Final Trials of Humanity.
Understanding human desires came naturally to him.
Afterward, Ren stayed in the Jura Forest for several more days, discussing the finer details of the underground labyrinth with Rimuru.
Only after everything had been finalized did he finally return to the Kingdom of Falmuth.
The king who was infamous for his lolicon tendencies had disappeared for several days again—
Yet the kingdom continued functioning perfectly well.
After all, for the people of Falmuth, their king's occasional disappearances had long since become routine.
Soon after returning, the king issued a brand-new decree.
Merchants within the kingdom were instructed that whenever they traded goods with foreign merchants…
They should randomly include a special card as a gift.
On the front of the card was the image of a massive labyrinth.
On the back were portraits of Milim, Veldora, Ramiris, Rimuru, and Ren.
The official name of the card was announced as—
"Proof of the Strong."
It was declared to be the only pass that allowed entry into the underground labyrinth.
And only those who collected all five cards would earn the right to challenge the strongest labyrinth in history.
At first, foreign merchants visiting Falmuth didn't take the card very seriously.
They simply assumed it was some kind of commemorative item.
Still, none of them dared throw it away casually.
After all, the craftsmanship of the card was exquisite.
And the five figures depicted on the back?
They were individuals no sane person would ever dare offend.
However—
As rumors began spreading…
A knight from the Kingdom of Falmuth publicly claimed that he had attempted the challenge of the legendary grand labyrinth.
Although he had only managed to clear the tenth floor, he had been fortunate enough to obtain a small blue crystal.
After using it—
His strength had increased dramatically.
Moreover, during the two days he spent fighting inside the labyrinth, he could clearly feel his combat experience improving.
And after absorbing the power of that mysterious crystal…
His overall power had skyrocketed.
Even more surprising—
Although the monsters inside the labyrinth were incredibly dangerous…
The dungeon was also filled with opportunities.
And if a challenger ever faced a life-or-death crisis, they could simply tear apart one of their cards.
Doing so would instantly teleport them outside the labyrinth.
...
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