"Yo, Rei. You're finally here. Took you longer than I expected."
As Rei stepped into the Guild warehouse—a space that might more accurately be called a temporary Alchemy research laboratory—those words reached his ears.
Rei and Vihera both turned their gazes toward the source of the voice.
Standing there, exactly as Rei had expected, was Asimov.
Whether it was the work itself, or rather the sheer joy of being able to throw himself fully into his hobby, he wore an expression of deep satisfaction.
"Judging by that look on your face, I take it you really were the one who built this Unbris detector."
The successful creation of the Unbris detector—that was what he had been told in the carriage.
Rei had been surprised when he first heard the news, but given that Asimov was capable of creating a powerful Magic Item like the Twilight Spear, it wasn't hard to believe he could extract Unbris residue and build a detector from it.
At least, that was how Rei saw it, and judging by the current state of the warehouse, his assessment wasn't far off the mark.
"Death Scythe was a bit beyond me, but the Twilight Spear is a Magic Item I made myself. Starting from there wasn't all that difficult."
"…I'd still think that's quite difficult, even under normal circumstances. But only I can use it?"
"Yeah. Given more time, I could probably adjust it so anyone could use it… but unfortunately, they wanted a working prototype they could put to use as quickly as possible."
Asimov muttered with a hint of regret, and the surrounding Alchemists wore similarly disappointed expressions.
(They're all the same type, huh.)
The thought crossed Rei's mind, but he decided now wasn't the time for such observations and spoke up.
"In other words, the reason you called me here at this hour is to confirm whether the detector actually works?"
There was a hint of exasperation in his voice, but he also accepted that it couldn't be helped.
Right now, the Unbris was the top-priority threat in Gilm that had to be dealt with.
Given that, if a detector had been completed, they needed to verify as quickly as possible whether it functioned properly—and if it didn't, figure out why.
And if it worked without issue, the next task would be modifying it so anyone could use it, not just Rei.
(Come to think of it, the fact that Vihera and I were woken up means these guys pulled an all-nighter, doesn't it? …Well, maybe that's not so surprising.)
For people who had turned their hobbies into their livelihood, an all-nighter probably posed no particular hardship.
"Yeah, that's right. So, can you try it out for us right away?"
What he handed over was a palm-sized Magic Item.
In shape, it was flat, as though a crystal had been crushed.
Inside the crystal, however, there was black mist—something resembling Unbris residue was contained within.
"Another odd shape. …So, how do I use it?"
"Just pour your magic into it, that's all. After that, the black thing inside the crystal will move toward wherever the Unbris is, so if you head in that direction, you should reach it."
"…What happens if there are multiple Unbris?"
"It'll point to the location of the nearest one… probably."
The slight uncertainty in Asimov's voice was no doubt because they hadn't actually been able to test it.
The fact that only Rei could use this Magic Item was holding them back.
"In other words, you want me to try it out."
When Rei asked, Asimov and the other Alchemists nodded.
"Got it. …Here I go, then."
With that, he channeled his magic into the detector in his hand.
The Unbris residue inside the detector slowly began to move.
"Ooooooh!"
The Alchemists watching all raised their voices in unison.
Since it was a Magic Item they had built themselves, they must have been confident it would work. But that confidence was based on never having actually tested it—it was essentially an armchair theory.
That was why the joy they felt upon seeing the Magic Item actually move was apparently all the stronger.
(Huh… so it moves like this.)
Looking at the Magic Item in his hand, Rei observed it with admiration.
Within the flat crystal, the black mist was drifting toward the front-right diagonal.
Then, inside the flat crystal, it gradually shifted from the front-right diagonal toward the front—only slightly, but steadily moving toward dead center.
This meant that the Unbris the detector had found was moving from right to left.
"So Unbris is active even at this hour. …Can I take this detector with me? You used Unbris residue to make it, right? Doesn't that mean if I take this, you can't make another one?"
It could only be used by Rei for now, but eventually it would be made usable by other adventurers as well. Remembering that, he asked, and Asimov returned a confident nod.
"What's inside that detector isn't all of the Unbris residue we extracted from Death Scythe and the Twilight Spear. We've kept a certain amount here in reserve, so don't worry."
"Nothing gets past you. …So it's fine if I take this detector, right?"
"Yeah. Since you're the only one who can use it, honestly there's no point in keeping it here. Well, we can always review it again for reference if needed."
Asimov all but said that since the detector worked, they had no more business with Rei.
Rei felt slightly irritated by the exchange, but before he could open his mouth to respond, Asimov spoke up again.
"Death Scythe and the Twilight Spear are over there, so take them. Death Scythe was a bit beyond even me, but I made fine adjustments to the Twilight Spear. Well, it's not like I added any new functions—just maintenance."
"…Weren't you busy with the Unbris situation?"
"Hmph, something this simple can be handled by anyone, not just me. More importantly, hurry up and go. You still have things to do, don't you?"
Asimov turned his face away from Rei as he said that, but a female Alchemist who had been standing a short distance away approached Rei.
"Hehe, Asimov-san actually cares a lot about you, Rei-san, despite how he acts. When separating the Unbris residue from the borrowed Magic Items, he didn't leave it to anyone else—he did it himself."
"Hey! Wersha! Stop talking about things that don't matter and get over here! We're starting work!"
"Gyah! I-I know! Stop yelling at me!"
Startled by Asimov's booming voice, the female Alchemist—the woman called Wersha—headed toward Asimov while grumbling at him.
Then the Alchemists, led by Asimov, began discussing how to make the detector usable by anyone, each voicing their own opinions about what might work and what might not.
With the Alchemists clustered together exchanging their various opinions, the area around Rei naturally grew quiet.
"Hey, do you think there was any point in me coming?"
Vihera muttered under her breath.
They had been called out at such an hour to determine whether Rei could use the detector.
In other words, despite being dragged out of deep sleep and brought all the way to the Guild, Vihera had absolutely nothing to do.
Just being there. Being hauled to the Guild at this hour simply to exist in that state was not something she could easily accept.
"But if we'd only called Rei, you would've been angry, wouldn't you?"
A familiar voice came from behind, and Rei and Vihera turned around.
Standing there was Marina, wearing her usual party dress.
Whether she had still been awake in her capacity as Guild Master or had been roused early in the morning like Rei and the others, Rei couldn't tell. But either way, Marina showed no signs of fatigue as she made her appearance.
Vihera smiled and nodded at Marina.
"Of course. If you're going to call Rei, you'd better call me too."
"Then don't complain. …So, I just got here, but judging by that scene, the detector didn't work?"
Marina asked, eyeing the Alchemists as they argued heatedly among themselves, but Rei shook his head.
"No, it worked without any problems. We confirmed that the detector functions properly. Right now, they're discussing how to modify it so anyone can use it, not just me."
"…Honestly, I don't think a detector for finding Unbris—which appeared once three hundred years ago and has now reappeared—is going to be particularly practical."
"You're right. But there's no guarantee that Unbris will only appear here, is there? If that's the case, it'll be useful when Unbris shows up somewhere else. Besides…"
Marina flashed an alluring smile and directed her gaze toward the detector in Rei's hand.
"It's not as if that detector can only find Unbris, right? Right now it can only detect Unbris, but what do you think would happen if it could also locate other monsters?"
"Subjugation requests would become a lot easier."
"Exactly. Plus, you could head straight toward your target monster's location, so you wouldn't waste time running into unnecessary monsters along the way."
"That would be… convenient."
If there was one difficult thing about subjugation requests, it wasn't just defeating the target monster—it was, above all, finding the creature in the first place.
Unless you caught one while it was sleeping, monsters were usually on the move.
Successfully encountering a moving monster depended heavily on an adventurer's tracking skills and a fair amount of luck.
But if a detector could tell you exactly where the monster was, the success rate of subjugation requests would undoubtedly rise.
"…Well, actually reaching that point is probably a long way off, though."
Marina murmured quietly, just loud enough for Rei and Vihera to hear.
"Hm? Why? If this Magic Item could be adapted for use beyond Unbris and mass-produced…"
"That's the difficult part."
Marina declared flatly in response to Rei's words.
Seeing the puzzled looks from Rei and Vihera, Marina smiled and continued.
"That detector you're holding, Rei… it required a considerable number of rare materials to create. Enough that we're not just talking Platinum Coins—it could potentially reach the value of a Light Gold Coin."
"…Seriously?"
With some trepidation, Rei directed his gaze toward the detector in his hand.
Judging by the palm-sized flat crystal, it certainly didn't look as though it had been crafted from such rare materials.
But he couldn't imagine Marina lying in this situation, which meant the detector currently in his hands was undoubtedly an object of that level of value.
"A Light Gold Coin, huh. I understand using materials of that value when creating a Magic Item, but…"
What crossed Rei's mind was the Twilight Spear.
Many of the materials used in it were rare, and if he hadn't brought his own materials and had an Alchemist procure everything, it would certainly have cost enough to require a Light Gold Coin.
(Well, if you were actually trying to buy something like the Magic Sword Noise used, it would easily cost a Light Gold Coin.)
Thinking of it that way, the Twilight Spear had been made remarkably cheaply thanks to him providing the materials himself.
"You understand, don't you? Mass-producing something at that price is difficult, and even if it were possible, only a handful of people could afford it."
"…What about having the Guild lend them out?"
"I understand Vihera's suggestion, but that would be a bit difficult too. If it were at least a Silver Coin… no, even a few Gold Coins in value, lending it out would be feasible. But we can't go around lending out a Light Gold Coin Magic Item."
That was partly because of the risk of someone absconding with it, and partly because of the danger of it being destroyed or lost in the heat of battle.
The Guild in Gilm, thanks to its geographical location on the frontier, was able to gather rare materials.
Because of that, it had more financial leeway than Guilds in other cities, but that didn't mean it was so wealthy it could afford to toss Light Gold Coins around without a care.
"If it could be made more cheaply, that would be a different story… but anyway, right now Unbris takes priority over all that. I can't ask you to go out this very moment, but once the city gates open, can you head out?"
"Yeah."
Nodding at Marina's words, Rei turned his gaze toward the detector in his hand—the key to defeating Unbris.