Elena and the others had been watching the knight's dismayed expression, but it was Vihera who broke the silence first.
"So, Rei. What exactly is that fire burning? I'm curious about how a lake suddenly appeared here too, but that concerns me even more."
Even as she said this, she kept her gaze on the lake—likely because she understood that whatever had come from it had attacked Rei.
They had seen the massive flame, and upon arriving, found a giant lake waiting for them.
Given that, where the burning entity had come from was obvious without needing to think about it.
"Simply put, there was a giant Slime at the bottom of the lake. One big enough to mistake for a hill or a mound."
"A Slime, huh."
Hearing it was a Slime, she wore a slightly disappointed expression.
For Vihera, a Slime wasn't a particularly enjoyable opponent to fight.
To defeat a Slime without magic, one had to destroy its core—the Magic Stone.
That was manageable enough for an ordinary Slime, but with a giant one like the one Rei had fought, destroying the Magic Stone would be a daunting task.
What's more, a Slime's Magic Stone could be semi-transparent or move freely within its body, making it difficult to find.
In fact, even while fighting the Slime before him, Rei had never figured out where the Magic Stone was.
That was why he had wondered whether this Slime, having possibly come from another world, might not even possess one.
"Yeah. It was quite a troublesome one. ...Well, I should say 'is' rather than 'was.' It's not dead yet."
"...It's not dead?"
Looking at the still-burning Slime, Marina... no, all the newcomers stared at the flames in dumbfounded astonishment.
Though they couldn't feel the heat, anyone could easily grasp how powerful that fire was just by looking at it.
That was exactly why they couldn't comprehend how something being consumed by those flames could still be alive.
"The fact that the fire keeps burning is proof that the Slime is still alive. ...The fortunate part is that while it's being burned, it can't do anything."
"If it's a Slime, they don't feel pain or anything, so you'd think it could act normally even while being burned."
"All I can say to that is—it's my magic."
"True. It is you, after all."
She let out a sigh tinged with mild exasperation—and above all, disappointment. She had come hoping to enjoy a battle with a formidable enemy, only to find that Rei's opponent had been a Slime.
That said, even if it was an opponent she struggled against, it was unquestionably a strong enemy. If a Slime were still here, Vihera would likely have challenged it to a fight.
Thinking about it, asking Marina to handle this is slightly concerning.
If it turned out there were more Slimes at the bottom of the lake, Vihera would undoubtedly challenge them to battle with glee.
She wouldn't show the slightest concern about them being a bad matchup... no, rather, she'd see overcoming her weakness as the very reason to fight. The image of Vihera eagerly challenging a Slime flashed through Rei's mind.
...But even so, they couldn't very well leave the lake's safety unconfirmed, so Rei called out to Marina, who had been listening to their conversation with keen interest.
"This is related to the Slime business, but I have a favor to ask of you, Marina."
"A favor, huh. ...If you're asking me to do something about that burning Slime, it's impossible. I don't have good compatibility with fire spirits to begin with."
"No, not that. The truth is, I want you to investigate the inside of the lake using your Spirit Magic. This lake would be of enormous benefit to Gilm—that much is certain. But if there are other monsters like that Slime in the water, we can't exactly fish there carelessly."
At Rei's words, Marina nodded in understanding.
Elena, who had been observing the lake nearby, also nodded in agreement. If they were to investigate the lake, asking Marina—who had good compatibility with water spirits—was by no means the wrong choice.
"Fishing, huh. That does give me a bit more motivation. In Gilm, fresh fish are inevitably hard to come by. ...Though thanks to Rei, we never have to worry about that at all."
Ever since Rei started eating meals at Marina's house, large quantities of fresh fish stored in his Misty Ring had been provided.
But that was only possible because Rei stored fish he caught at sea or in rivers in his Misty Ring.
Beyond that, it was only because of Set that they could casually go out to sea.
Such things were only possible because it was Rei. Normally, one couldn't eat fresh fish in Gilm.
However, with this lake, it was a different story.
It's probably a lake that teleported from another world, so I don't know whether the fish there are edible. ...Well, Zozo and the others ate fish from this world, so maybe it's fine? Then again, there's no guarantee this lake came from Zozo's world, which makes it hard to judge.
Rei turned his gaze toward the lake as well.
He could only hope that there were no other entities like the still-burning Slime lurking within.
"Can you do it?"
"Yes, leave it to me. Though rather than having spirits investigate for me, it'll likely take the form of asking the water spirits residing in this lake. I'll get started right away, if that's alright?"
Nodding at Rei's words, Marina began speaking to the water spirits...
"Hm?"
She suddenly stopped.
Because Rei—and everyone else around them—had absolute trust in Marina when it came to Spirit Magic, they all directed puzzled gazes her way.
"Did something happen?"
"...The water spirits in this lake seem to be difficult. I'll explain that part later."
Difficult? Rei wondered.
He had thought that Marina, with her good compatibility with water spirits, would be able to investigate the lake's interior right away.
But considering her meaningful glance, it was highly likely that "difficult" was some sort of pretense.
Spirits... spirits? Ah, maybe because the lake came from another world, the spirits have different personalities or compatibility? For that matter, there was even the possibility that no spirits existed here at all.
While nothing was confirmed yet, Rei pondered what was likely the correct answer and quietly watched Marina's progress.
Everyone watched her movements... and after a few minutes, a sphere of water about one meter in diameter floated up from the lake and drifted before Marina.
A ball of water traveling through the air would be an astonishing sight to those unaccustomed to it, but with Marina around, it wasn't all that rare.
Then, the spirit eventually returned to the lake.
"Phew."
Letting out a small breath, Marina looked at Rei with a smile—the kind that, as always, carried a strong feminine allure—and spoke.
"I tried asking the water spirits for now, and it seems the giant Slime that Rei defeated... is defeating? ...Anyway, it appears to be the only one."
"You gathered all that information just from that?"
"Yes. That water spirit was originally in this lake, after all. It seems to have a general grasp of the lake's conditions. ...The problem is that communication is difficult."
Hearing those last few words murmured quietly, Rei understood why she had struggled at first.
I don't know exactly how she communicates with spirits, but maybe spirits are like Lizardmen with different languages? No, but she managed to communicate quickly enough.
Regardless, Marina's words were enough to put Rei at ease.
"By the way, are there any other dangerous monsters besides that Slime?"
"Hmm... that's the thing. Like I said, communication is difficult."
Marina told him with a troubled expression, but didn't offer any further details.
Whether she judged it better not to say it here, or simply thought they wouldn't understand even if she explained about Spirit Magic, Rei couldn't tell.
But regardless, he steered the conversation back to the lake.
"The lake might not be completely safe, but just knowing there are no other entities on the scale of that Slime is a huge help. The next problem is... whether the fish caught in this lake are edible."
If this lake had come from another world, its fish would naturally be unknown as well.
At the very least, if the lake had come from the same world as the Gran Dragonia Empire... Rei entertained a hope he didn't entirely believe himself.
If the lake had teleported from the world where the Gran Dragonia Empire existed, there was a high chance Zozo and the others would know its fish.
But if the lake had, as Rei suspected, teleported from a third world—neither this one nor Zozo's—they would first need to investigate which fish were safe to eat.
After all, there was no guarantee that some fish wouldn't carry poison like pufferfish.
If there were delicious-looking fish like pufferfish, people might rush to eat them first, potentially spreading poison casualties.
...Though Rei himself had never actually eaten pufferfish.
"We'll just have to look into that gradually. We can't exactly ask the spirits, after all. ...We can't ask them, right?"
Vihera asked Marina with a just-in-case tone, but was met with an expected shake of the head.
"Figured. In that case, we'll need to start by catching fish and such... I wonder just how many species are in this lake."
"Ah... yeah. That sounds incredibly tedious to investigate."
Rei chimed in with a sympathetic tone at Vihera's words.
The lake stretching out before them was truly vast.
Just thinking about how many species of fish might be in it was exhausting.
Moreover, there would be shellfish and crabs as well, and there were also the animals Rei had spotted from the sky while flying on Set—the kind with fur that didn't get wet at all even in the water.
Investigating all of them would undoubtedly require considerable effort.
Rei recalled a TV special he had seen in Japan about how new species were discovered almost daily in the Amazon.
Of course, this lake wasn't as vast as the Amazon, but coming from another world as it did, it would inevitably be full of unfamiliar species at first.
Still, unlike Japan... no, unlike Earth, there was no need to register new species upon discovery. And rather than causing a stir over new species of fish, plants, insects, or shellfish, only new monster species would warrant such attention. This was characteristic of this world... or rather, characteristic of the Frontier.
After all, the very reason it was called the Frontier was because countless unknown monsters and animals inhabited it, so new species were not particularly rare.
"We'll take care of that bit by bit. Scholars... or rather, alchemists would likely get enthusiastic if there are materials they could use. And with so many unknown creatures, pharmacists might get eager too. We can't deny the possibility that plants growing along the lakeshore have some kind of medicinal property."
"Those types would probably come to this lake with glee. At any rate, according to the water spirits, it seems safe."
"That's right. However, that only means there are no monsters as powerful as the burning Slime. We can't rule out the possibility of other types of monsters entirely."
Even if they weren't as fiendish as the Slime that had attacked Rei and was still burning, it wouldn't be strange for creatures that attack humans to exist.
Especially with a lake this vast, there was no telling whether fish-type monsters might be present. ...No, it was better to assume they definitely were.
Given that this lake teleported from another world, it wouldn't be strange for there to be a third type of existence that is neither fish nor monster, either.
At the very least, it would be nice if they could determine clearly whether this lake had truly come from a third world, or simply came from Zozo's world but was a lake Zozo and the others didn't know about, or whether it came from a nation other than the Gran Dragonia Empire.
Thinking this, Rei turned his gaze back to the still-burning Slime.
A considerable amount of time had already passed since it started burning, but there was no sign of it burning out.
The sight of it burning endlessly was, honestly, enough to make even Rei—who had cast the magic—wonder just how long it would keep going.
Perhaps it would continue burning for the rest of today... no, for days, or even dozens of days... possibly even longer than that. Thinking this, Rei's expression took on a subtly displeased look.