That room is located deep within the central basement of Renya's castle.

Such a room would never be reached by only passing through the normal hallways.

At the beginning sorcery light had been installed in the passages that must not be used, but before long the illumination ceased, and the leading Frau invoked a sorcery light at her finger tip, brightening up the passage for Keith's and Mayria's sake who were following her.

That means that Frau would normally be capable of following this route even without light.

Keith's complexion, who was moving forward through the dark passage while relying solely on the light created by Frau, is bad, but Mayria has fear clearly showing on her face. She grabbed Frau's shoulder so as to not get separated.

Tell me, why are you so scared ~no? (Frau)

While apparently being very annoyed that her shoulder was being pulled by Mayria probably because of the difference in their heights Frau asks the two behind her.

Wouldn't it have been fine if they hadn't asked to come along, if they were going to be so anxious throughout the trip? Frau wonders, but neither Keith nor Mayria relaxed their worried expressions while seemingly being curious about their surroundings, bearing a sense of responsibility or more simply, going for the thrill of the scare, but as a consequence they haven't proposed to go back either.

Even if you see it, it's nothing of interest ~no. (Frau)

Muttering that as a complaint, Frau soon arrives in front of a single door.

Usually the doors set up in the castle were sturdy as they were made out of wood and metal plates, but the door at which Frau stopped is completely made out of metal. Its sturdiness exceeds that of the other doors by far.

Densely packed, character-like symbols were carved onto its surface, but not to mention Keith, even Mayria, who should possess a wide range of knowledge, doesn't know who uses such characters.

Just what are these characters? (Mayria)

At first Mayria and Keith believed it to be some kind of patterns, but since they immediately realized that each of those patterns is lined up with some kind of regularity, they judged them to most likely be characters. However, even when closely looking at the characters, they are still unable to read them.

Those are simple patterns ~nano. (Frau)

Frau says, obviously betraying their conclusion downright.

It's something similar to a security system hindering people, who ended up arriving here by some kind of mistake, to become alert and touch it just because it seems to be something vaguely suspicious ~nano. (Frau)

I see? (Keith)

Seemingly believing that there's some truth to that, Keith agreed, but Mayria apparently couldn't come to terms with that explanation. She's still firmly grasping Frau's shoulder, but her eyes keep tracing the door's surface.

You're too distrustful ~no. (Frau)

Once Frau placed her hand on the door while smiling wryly, the door, which should be considerably heavy, slowly opened towards the inside without causing any sounds.

Keith and Mayria resolved themselves to the extent that they'd be able to say, No matter what I see on the other side of the door, I won't be surprised, but in the end they still end up surprised by the pure space, which was just like the deep part of a forest, spreading out on the other side of the door.

The inside of the temple bell-shaped room, which possessed a considerable size, was overflowing with so much brightness that it made the two, who had advanced through a dark passage, feel slight pain in their eyes.

Unclear about what kind of device it is, a brilliant, pure-white light is pouring down from the ceiling.

Something like a water well can be seen exactly in the middle of the room. The transparent water that copiously gushes out from the well is divided into several aqueducts that have been built in a radial setup spanning from the room's center to the walls. Once the water reaches the walls, it falls into a gutter-like channel.

Even though there's plenty of water gushing out from the well, the water level in the gutter doesn't change at all. Upon closer inspection, a waterway, where the water seems to stream towards a different location, has been installed under the gutter.

Various kinds of plants, which seem to weave their way through the gaps in the simple stone wall, are thickly populated with leaves. Moreover, quite a few plant roots, which are seemingly passing through the gaps in the wall, extend themselves towards the waterways, soaking in the clear water.

Since there was a great water vein right below the castle, we're drawing its water to this place ~no. (Frau)

Keith and Mayria, who imagined something a lot more frightening as Frau had said that it would the core of the defense, survey the room's interior with disappointed expressions.

Going by the visible impression, it's a scenery that could even be called an exclusive garden.

Speaking of slightly strange parts, you'd have to mention that there's not a single indication of soil being present, albeit it being a place overgrown with plants.

This place is the core of the defense, you say? (Keith)

Keith raises as question, unable to swallow Frau's words, no matter how he looks at it.

Frau nods shortly at that.

The spring water of this place passes along many magic stones, and the water, which is then abundantly rich with mana, is spread throughout the city's underground ~no. That water greatly contributes to the growth of the plants within the city. And those plants are going to resolve the provision of food during the defense and the strengthening of the outer wall ~no. (Frau)

Once they are told by Frau, While we are at it, the fact that there are plenty of plants that contain great amounts of juice also becomes a countermeasure against fire attacks for the city ~no, even Keith begins to think that it might make sense.

How to say it? Plain, isn't it? (Keith)

Unable to admit directly into Frau's face that he expected it to be an outrageous facility which would be eerie and impossible to understand, Keith states a harmless and inoffensive impression.

Keith, just what have you been expecting ~no? (Frau)

Once he was glared at by Frau's scornful eyes, Keith scratched the back of his head while raising a powerless laughter.

This place is right below master's home ~nano. No matter how you look at it, I couldn't have set up something as strange as you've been expecting, Keith ~no! (Frau)

Well, that makes sense. I wouldn't be able to calmly sleep if a dragon opened its mouth right under my bed either. (Keith)

If you got it, then return to your post at once ~no. Neither of you should be in a position where you have the time to play around ~nano. (Frau)

Keith kowtows towards Frau who bluntly announces that with both her hands pressed against heir hips and a rough nasal breathing.

Just as Keith is about to leave the room in order to escape from Frau, he notices that Mayria hasn't moved from her spot.

Mayria was squatting close to one of the aqueducts with her eyes closed partly and an expression that seemed as if she was somewhat entranced.

Mayrisama? (Keith)

Yeah, I will stay here a bit longer. The air here is nice. It feels really good. (Mayria)

UmmI will go back by myself, I guess? (Keith)

Once you enter the branch passage, it's basically a straight path as long as you don't open any strange doors ~nano. (Frau)

Frau stared at Mayria who showed no intention of going back, but once she grasped that Mayria really didn't have any interest in moving, she added a sorcery light to the hilt of the longsword worn by Keith.

Keith, you're a good adult, so you will go back by yourself ~no. Mayrisama will later be escorted by Frau ~no. (Frau)

Roger. Well then, excuse me. (Keith)

Keith leaves the room after bowing with a short bob of his head.

After he was out of sight, Frau closed the room's door and cast a fleeting glance at Mayria who was still crouching.

It was just a split second that Frau's eyes were turned towards Mayria, but seemingly having perceived it, Mayria opens her eyes, and said while looking at Frau with upturned eyes,

Now then Frau-chan, where's the real core? (Mayria)

I don't know anything about a real core or whatsoever ~no. (Frau)

Frau's voice is the same as usual.

But, hearing her, Mayria warped her expression a tiny bit and sighed.

So you won't tell me either, huh? Somehow that's quite saddening. (Mayria)

This place is truly the core part ~nano. (Frau)

Location-wise you mean, right? Putting Keith-san aside, if I'm told that a water vein source and aqueducts, which provide the entire city with mancharged water, are the defense core, then I wouldn't believe something like that, you know? (Mayria)

I haven't told you any lies ~no. (Frau)

Yes, I haven't said anything about you lying either, Frau-chan. But, there's something you haven't shown us, isn't there? (Mayria)

Once Mayria says that while cracking a smile, Frau dropped her shoulders and sighed.

Silently Frau looks at Mayria and points towards the entrance door with a finger, urging her to go outside for a moment.

Mayria, who judged that Frau felt inclined to show her the real core, stands up obediently and leaves the room along with Frau.

In reality I don't really want others to see it ~no. (Frau)

Voicing such a thing out with a touch of reluctance, Frau closes the heavy, metallic door and makes her finger trace along the patterns drawn on the door's surface which she previously called simple.

There seems to be some underlying principle in the places she traces. In front of the observing Mayria, the parts, which were touched by Frau's finger, started to emit a white light.

I won't take any responsibility even if it causes some kind of abnormality in your mental state ~no. Are you still willing to go ahead with it ~no? (Frau)

The threatening tone being included in Frau's voice could be said to be reasonable.

As a matter of fact, when she showed it to Emil, Emil said that the best outcome that could come from timid people or mentally weak people seeing it would be them fainting.

Frau was given the detailed instruction by Emil to warn people that it will very likely induce a mental disorder if things go the wrong way.

You have installed something so dangerous here? (Mayria)

Mayria is surprised and shocked by the contents of Frau's warning, but the option of not seeing apparently doesn't exist in her mind.

While continuing the process of opening the door, Frau secretly prepares herself in order to use the spell at any time.

If Mayria transformed into a bedridden puppet that only laughs foolishly from seeing it, Frau couldn't predict what ordeal she would have to go through once Renya returned.

First of all, there's absolutely no way that it'll simply end with him saying Oh okay, I guess it can't be helped.

Well then, I'm going to open it ~no. Hold onto your mind properly ~no. Okay? (Frau)

While nodding towards Frau's words, Mayria quietly chanted something.

Frau immediately notices that it's the spell she was preparing herself just in case.

The spell calms down the target's mind if it's afflicted by something very disturbing. It's a spell that can suppress mental damage even if the target experiences something that would make them go crazy after some time under normal circumstances.

If you take this action into consideration, it can be seen that even Mayria herself apparently understood that the thing, which Frau had decided to deliberately show her, is something uncommon.

Having finished the process, Frau opens the door.

Just moments ago it should have been a door from which dazzling light and normal air leaked out, but now dark brownish light, a disgusting air blended with a nasty smell, and a heat that makes one want to turn away leaks out.

Due to Mayria instinctively covering her mouth, Frau quietly handed her a handkerchief.

Once Mayria receives the handkerchief, which was soaked with some herb-like scent which Mayria didn't recognize she tries to drown out the bad smells by pressing it against her mouth and nose, and follows after Frau, who had already entered the room first.

The room had completely changed compared to the one she had previously entered with Keith.

The room had the same temple bell-like shape, but there's absolutely no light pouring down from above, and there's only a wide gaping hole, from which the dark brown light seems to originate, located in the center of the room.

Even the walls are riddled with many holes, but as they are filled with darkness, it's unknown as to what could be dwelling within.

A red, gooey liquid bubbles upwards from within the wide gaping hole in the center, giving one the impression that it's the crater of a volcano at first glance.

Each time one of the bubbles burst, a hot stench seemed to spread into the vicinity.

However, if it were only that, it would have been no more than a smelly, hot hole.

Thinking that there's probably nothing that could cause one to lose their mental sanity either, Mayria peered into that hole over Frau's head, and then her expression froze.

That red, gooey liquid seemed to have a degree of transparency which was unexpected given its viscosity. The peeking Mayria's eyes directly met with something that's submerged within the liquid.

Countless eyes.

Furthermore, things that had assumed human shapes.

They, which extended their arms as if struggling while slowly swaying within the liquid, were in a state that made their body contours ambiguous, making it difficult to specify their gender or age, but for some reason only their eyes were clearly visible.

With the whites of their eyes becoming bloodshot and the pupils widening, they opened their eyes to the very limit, looking at Mayria with gazes that seemed to be beseeching her in some way.

The sight of countless such stares being submerged inside the liquid can't be described with only the word abnormal.

Due to nausea reflexively welling up in her stomach, Mayria tightly gritted her molars and endured.

Frau-chanthoseare? (Mayria)

They are still alive within the water that's full of mana ~no. From the start they were various spies or assassins from somewhere ~no. But, once they are dropped in here, the same fate awaits all of them ~nano. (Frau)

Frau says with an emotionless voice.

This is the power source for almost all sorcery interception devices located in Klinge. It's the main body of the defense's core. Since they are conscious individuals, their negative emotions are exploited and converted into manait's a device that's referred to as Hell Furnace ~nano. (Frau)

The name of the device mentioned by Frau was something Mayria had never heard before.

Even Frau isn't aware of the details ~no. Frau didn't design it, it was someone else that designed this furnace ~nano. All that Frau knows is that once you toss magic stones and sacrifices into this place, the furnace operates by consuming a part of the magic stones' mana while feeding on the negative emotions of the sacrifices. Amplifying the remaining mana of the magic stones, it produces an even larger amount of mana than the original magic stones. The generated mana is conveyed to all over the city through certain things located at the bottom of the furnace. That's the extent of my knowledge ~nano. (Frau)

Certain things? What do you mean by that? (Mayria)

Mayria asks driven by her curiosity, but Frau shook her head, expressionlessly.

It's better for you to know about it ~no. It's definiteeely the best for you to not know about it ~no. Because the sacrifices are pulled from the surface into the bottom of this furnace, and as it's for the sake of making sure that the sacrifices don't escape, huge clusters of tentacles are submerged in there in order to circulate the mana through the entire city. You won't be able to hear from Frau's mouth that something like massive tentacles are stretching out below the city ~no. (Frau)

You've said it (Mayria)

Previously Keith said that it would be unbearable for him if a dragon were to open its mouth below his bed.

However, if you consider the actual circumstances, those words still described a much better situation than this here, Mayria absentmindedly thought in a corner of her mind while still being paralyzed.

After all it wasn't only under his bed, she had been told that these strange things are transporting mana all over Klinge's underground and that there have been countless tentacles laid out for the sake of dragging suspicious people into this furnace.

I wonder, isn't dealing with Frau and the designer of this furnace an even more urgent problem for humanity than the demon king?

While watching the surface of the red liquid that spit out yet another bubble with a blub sound, Mayria strongly decided in her mind to consult Renya about this matter once he gets back.

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