Uncomfortable Cohabitation (7)
I opened the entrance to the underground waterway and stepped inside. At first I'd been worried the place would reek and be filthy beyond bearing…
"It's cleaner than I expected?"
I'd been ready to cast purification magic, but it wasn't nearly that bad.
"Perhaps only because we're still at the entrance?"
Priest Daniel was being cautious. Fair enough—he had a point.
As we started down the stairs, an unpleasant smell gradually rose to meet us. Not sewage or excrement, exactly—more like the damp, musty odor of stagnant water.
When we reached the bottom of the stairs, a vast space opened before us. The entire chamber had been built of stone. A channel of flowing water ran down the center, and on either side stretched walkways wide enough for two people to stand abreast. Even those paths were paved in stone. Honestly… the underground waterway felt remarkably modern.
This went well beyond a mere stone cave. Everything had been cut and fitted with deliberate precision.
"The, uh… the construction quality is impressive…"
"It has to be. Without this level of workmanship, the whole thing would collapse."
Ah… so that was why they'd built it properly.
"The project was carried out under the kingdom's authority—specifically in the name of the royal family."
A construction of that scale… if something went wrong? If the ground subsided? How would people judge the royal house then?
"At the time, the royal family is said to have devoted the full strength of the nation to the work."
"This underground waterway technology… it feels familiar."
Priest Daniel suddenly said something odd.
"Familiar?"
"Yes. I believe the dwarven cities—and the temples of the God of Fire—were built with a similar structure."
"Temples of the God of Fire?"
"Yes. Dwarves dig into great mountains to create their cities."
They settle in mountains rich with ore veins, mining minerals while expanding their cities and districts, or so the stories go.
"Yes, this is almost certainly that same technology. I don't know the details myself, but I've heard there was some exchange of techniques between the temples and the dwarves back then."
That was a story from more than a hundred years ago.
The division into upper and lower levels, the planned development—it all seemed to fit. In any case, the path was less filthy than I'd expected. The flowing water, which I'd assumed would be thick with filth, looked surprisingly ordinary.
Of course it wasn't clean water by any means, so caution was still wise.
"It's in better condition than I thought."
The entrance section, at least, was far better than I'd feared.
"The real trouble is further in."
That stood to reason. Sister Mary and I lit the way, consulting the map as we headed toward the section we were supposed to clear.
As we pushed deeper inside, the damp smell gave way to something stranger, and the distinctive reek of mold joined it.
"Ugh. So it really was only milder at the entrance."
I cast purification magic freely, scrubbing away the stench and any toxic gases.
"Aren't you using rather a lot of magic…?"
Priest Daniel, who didn't fully grasp the scale of my Holy Power, offered a concerned remark.
"You needn't worry. Julian's Holy Power is more than five times my own."
At Sister Mary's words, Priest Daniel fell quiet.
In truth, it might well be more than five times. And in my case, the recovery rate of my Holy Power was unusually fast as well…
"I—I see. As expected of one chosen by the Goddess."
He then began murmuring a quiet prayer.
"So please don't worry."
I cast another wave of purification magic ahead of us as I spoke.
"Yes. If it becomes too much, feel free to leave it to me at any time."
I smiled faintly. That would almost certainly never be necessary…
As we drew near our assigned section, monsters came into view.
The color was a little off, but they were unmistakably slimes.
"Those slimes look strange."
"They've been feeding on filth, no doubt."
The young master answered as if it were nothing, then stepped forward and cut through a slime with his sword. The blade, charged with mana, sliced cleanly through the creature's acidic body. The slime's form quivered and melted away. The young master casually plucked the core from within the remains.
"It seems to work like this."
There were still few enough slimes that we could handle them without much trouble.
"The colors really are unusual."
We continued through the section, clearing slimes as we went. The ones you usually saw aboveground came in solid colors—green, red, blue, gray. The slimes in the underground waterway, though, were mottled: gray mixed with brown, or green swirled with purple.
"They must have changed after living underground for so long."
Priest Daniel examined one of them carefully.
"There might be research value in these…"
Except there was no one on hand to research them.
"The mages who come down here don't seem interested."
"Anyone willing to come this far is hardly a scholar, so it can't be helped."
True enough. If you weren't a scholar, there was no reason to care about oddly colored slimes. They were easy enough to deal with and posed no real problem.
After walking for some time, we reached the far end of the section.
"This is…"
A wall of iron bars stood before us. Water seeped through the gaps, but a person couldn't pass. Conversely, the monsters on the other side couldn't cross over to us either.
"So they really are using walls like this to raise monsters."
Priest Daniel's observation made the purpose clear. They were penning the slimes and farming them.
"Then what about the slimes we found outside the section?"
"Smaller ones that slipped through the bars, or ones that wandered in from outside."
I nodded at the young master's assessment. The gaps in the bars were larger than I'd first thought.
"But even a slime's body can't dissolve this wall?"
I approached the bars carefully.
There was no flow of mana that I could sense…
"I don't know that either."
The young master had been serving admirably as our walking encyclopedia, but even he had his limits. How did these bars withstand acid that could corrode iron weapons?
"Well, it doesn't matter. Let's keep moving."
We worked our way through the area, eliminating the slimes that had strayed from their section and any monsters that had drifted in from outside.
In the process, I more or less grasped the structure of the underground waterway. Slimes were kept in designated zones connected to the places where waste was dumped. When their numbers grew too large, the excess was pushed out—and those were the ones we found wandering free.
"From the slimes' perspective, it's a steady supply of food…"
It was farming, pure and simple.
That was why they stayed put and kept living there. Competition still played out inside the pens: older slimes were weeded out, either eaten by younger ones or forced out of the zone. And to keep the population from exploding, people conducted culls like this—a system for maintaining numbers…
"More than that, there are quite a few monsters living hidden down here."
Besides the rat- and bat-type monsters, there were aquatic ones as well.
"Well, at least there are no strong ones. That's a relief."
If orcs—no, if ogres or trolls or other mid- to large-sized monsters had been living here? Though… could they even survive in a place like this?
"In my view, dealing with these monsters is important."
"Why is that?"
Uh… according to knowledge from my previous life, wild animals carried all sorts of pathogens that could transmit to humans. Monsters were animals in a broad sense, and living in an environment this filthy, they were bound to be crawling with disease.
But did the concept of germs even exist in this world? My past-life memories were tangled up with what I knew now, and it was getting confusing. Nothing for it.
"J-just a feeling? More importantly, I'm worried about leaving these corpses lying around."
No one seemed to understand why.
"D-don't they say that leaving bodies unattended after a battle spreads plague?"
"That's true."
The young master nodded.
"W-wouldn't monster corpses be similar? I know the water flowing through here isn't used as drinking water, but just leaving the bodies seems dangerous."
Slime remains were liquid and would simply wash away, but rats and bats were another matter.
"Burning them would be risky…"
With toxic gases present, setting fires wasn't practical.
"The client never told us what to do with them, so we can probably just leave them."
"This is harder than it looks."
Given the waterway's design, the water probably never seeped into the ground… but I still worried.
And one more question had taken root in my mind.
Where did the water that passed through here go?
What about the people in the villages and cities that used the river this waterway connected to?
In the modern world, water was treated at purification plants before being released again. But did this world have anything like that?
If I'd never known about such things, it wouldn't have bothered me…
Facing the reality of it now, I couldn't stop thinking about it.
"Is something troubling you?"
The young master approached with a look of concern.
"I-it's just… a question occurred to me."
"A question?"
"Yes. Where this water flows to, whether dirty water like this is really all right—things like that."
The young master smiled faintly.
"I can see why that would puzzle you."
He suddenly produced two maps.
"If you look carefully at the underground map, the waterways and the slime farms are laid out separately."
Zones linked together like a spider's web…
"Look closely—there are farms beneath the channels where the water flows as well."
In other words, after the waste was processed once, the water passed through yet another stretch lined with slimes?
"Run it through slimes several times like this, and the water should come out relatively clean."
So slimes had that kind of purifying ability…
I'd studied magic and a fair range of other subjects, but there was still so much I didn't know.
"I didn't realize slimes had purifying abilities like that."
So they weren't just there to dispose of waste…
With waste-processing spaces running all the way to the lowest levels, I probably didn't need to worry about the water.
"Does that ease your mind a little?"
"Yes. With so many people living in the Capital, I was worried about contamination."
In our village we collected that sort of thing and turned it into fertilizer… but here, they simply used slimes to purify it.
"The temples handle it in a similar fashion."
Priest Daniel offered an explanation I hadn't asked for. They made fertilizer as well, but with their surplus of manpower they also relied on purification magic, or so he said.
Magic and Holy Magic really were convenient.