The Mysterious Child: An Adventure Tale Beginning with Numerology

The next morning.

We left the inn and were traveling on the highway stretching straight south.

Normally, national borders are established using difficult-to-attack lands like rivers to secure control. However, the border of the Dragon Duchy of Bargia is simply the Dragon King's domain, so it's not affected by terrain. This is because there's an extremely skewed power balance where even the great armies of any country can't defeat the Dragon King alone.

It's hard to believe, but there's historical fact of tens of thousands of troops being wiped out by a single strike from the Dragon King, so it's not an exaggeration. The reason the Dragon Duchy of Bargia has reigned over the central continent for 400 years is due to this excessive strength of the Dragon King. Everyone agrees that it's fortunate the Dragon King has no interest in other countries.

In any case, the Dragon King is only interested in his own domain. The citizens who worship him built a huge wall along the borders passing through plains and forests to mark the domain, to prevent ignorant foreign enemies from incurring the Dragon King's wrath.

With such an obvious wall, and the faint presence of dragon-kind that can be sensed, this is the territory of the Dragon Duchy. Beasts that fear dragon-kind never approach the Dragon Duchy of Bargia.

This affects the ecosystem of forests and grasslands, with more intelligent monsters avoiding the direction of the Dragon Duchy of Bargia. The border wall, free from threats, continues uninterrupted like the Great Wall of China. We can occasionally see this wall from the highway we're traveling on.

"It's impressive."

I hadn't seen the Great Wall of China in my previous life. I had always wanted to see it at least once, so I was moved to be able to see a similar sight. Of course, the wall isn't close by, so we're just viewing it from a distance as we proceed.

Still, the Dragon Duchy of Bargia seems to have abundant resources. I wonder how long it took to build such a long wall. Was it a major national project like building the pyramids, mobilizing the entire population?

"It's amazing. Hey Elen, how much do you think it cost to build this wall?"

"Mm, earth magic."

"...Oh right, that exists."

I forgot because I can't use it myself.

Construction work in this world is a job for magic users, isn't it? Magic users aren't just for fighting. Although labor costs would be involved, they can create materials from local soil and rocks, so material and transportation costs would be minimal.

"Ah~ I feel like my sense of wonder is fading a bit."

I guess the pyramids or the Great Wall of China are better after all, yeah. As I was thinking about this, Roze pointed to something in the distance.

"We're almost there."

Near the long-stretching border wall, in a nearby forest, stood a mansion large enough to be visible from here. This was one of the reasons Roze came this way - the mansion where her former disciple lives.

□ □ □ □ □

"Welcome, teacher! Thank you for coming!"

The one who greeted us was a gentle-looking man wearing glasses.

He looked to be about 30 years old. He was slender and seemed unreliable, looking like someone who had lived a life far removed from fighting. Despite his apparent age, he was quite handsome. I had imagined Roze's disciples to be elderly, but this person didn't seem to fit that image.

"It's been a while, Prennarec."

"Yes, about 200 years, I believe."

I was mistaken. Looking closer, this person is an elf. So male elves are handsome too, huh.

According to the conversation, this male elf named Prennarec is about 280 years old. Like a typical elf, he doesn't seem to remember his exact age, but apparently, Roze was his teacher when he was a child.

"Please, please! Make yourselves at home in my mansion."

"I'll take you up on that. Is it alright if we stay the night?"

"By all means! Stay as long as you like."

Oh, this is rare. It's my first time staying at someone else's house. Prennarec's mansion is no smaller than the Muuteru family mansion where I grew up, so there must be plenty of rooms. He gave permission without hesitation.

First, we were guided to the reception room on the first floor. As we sat on the sofa, Prennarec also took a seat, and a young male servant placed fragrant drinks on the table. There's a familiar smell coming from this black drink... No, it can't be.

"Please, help yourselves. It's a specialty of our house."

"I'll have some."

"Thank you."

"Mm."

I bring the cup to my lips. As soon as the hot liquid enters my mouth, a fragrant bitterness and sweetness of sugar spread through it. There's also an acidity that rises to the nose, and overall, after a strong punch of flavor, a refreshing bitterness remains on the tongue. This is unmistakably... coffee!

"Hmm, as expected."

"It's delicious."

"Mm... bitter."

Seems like it didn't suit Elen's taste. But coffee, huh. It's the first time I've had it in this world, but I didn't know it existed here. As I was feeling impressed, Prennarec smiled and said:

"Once again, welcome to my home, teacher. Are these two your current disciples?"

"Yes, they are. Both of you, introduce yourselves."

"Nice to meet you, I'm Ruruk. I'm a 13-year-old human."

"Mm. Elenora. Sheep-folk, 22 years old."

We bowed our heads, and Prennarec responded in kind.

"Nice to meet you. I'm Prennarec, an elf and botanist, son of Kerkhule from the Juman Forest."

Oh, it's been a while since I heard an elf-style greeting. After greeting us safely, Prennarec stared intently at Elen's robe and said:

"But miss, you're a sheep-folk? I can't see any horns or wool, is that robe using the teacher's perception interference formula?"

"No, it's Ruruk's art."

"What! A human child, using this level of mystic art!?"

Now he's staring intently at me. Although he's a mature man, being stared at with such intense interest by a handsome elf is embarrassing, but if I could choose, I'd prefer a beautiful girl. A big sister type with a nurturing aura would be the best.

"I'm impressed. I've lived in human countries for many years, but even mystic art users are rare, let alone a child. As expected of you, teacher, you've found an excellent disciple."

"He's more of a problem child than I can handle, though."

Roze says with exasperation. I can't let that slide.

"What are you saying, Master? How am I a problem child?"

"Thanks to you, I've reaffirmed that ability and personality don't necessarily correlate."

"I have an obedient personality too! *sparkle*"

When I gazed at her with sparkling eyes, she just sighed. Why? Prennarec, watching this, gave a wry smile.

"Haha, Ruruk-kun is quite unique. Oh, that's right! Since you're here, would you like to meet my disciple as well?"

"Your disciple? You have one?"

"Yes. She's a bit shy but shows promise, so I'm teaching her while letting her live here. How about it?"

"Sure, I'll meet her."

As Roze nodded, Prennarec left the room. When he returned a few minutes later, he had a girl about my age with him.

"Come on, introduce yourself."

"I-I'm... Navi..."

Her voice was so small it was almost inaudible.

She was a girl with light blue hair braided into three plaits. Her bangs fell to her eyes, giving off a very shy impression. Wearing a simple skirt with an apron, she was probably an apprentice servant. She was still holding cleaning tools in her hands.

Since she was looking down, I couldn't see her face clearly, but she seemed quite pretty. She'll probably turn out to be a real beauty in the future.

"I'm Roze. I guess you could call me your master's master."

"I'm Ruruk."

"Mm, Elenora."

We greeted her briefly. The timid Navi jumped when I introduced myself and hid behind Prennarec. What's this about? Is there something about my name?

Still, her timid behavior reminds me of Lilith in the past. I honestly don't dislike this type.

"...What are you grinning about?"

"I'm not grinning (straight face)."

This is bad. I'm getting carried away with a girl I just met. For the sake of when she becomes a nice beauty in the future, I can't let her dislike me here. I should try to be cool. But how do I act cool? Just be normal, right?

"So, Prennarec. What kind of potential does this child have?"

Roze, who should be able to see talent and skills at a glance, deliberately asks out loud. Prennarec, seeming to understand the meaning behind this, answered immediately.

"She has talent in reasoning arts. Navi, would you mind sharing the reasoning formula you were thinking about the other day with Teacher Roze?"

"Y-Yes!"

Prennarec sat on the sofa with the nervous-looking Navi. He instructed a servant to bring a stack of papers, which he then spread out one by one on the table. They were covered with diagrams, mathematical formulas, and text. Prennarec, with an excited expression, asked Roze:

"Teacher, you're known as an embodiment of mystic arts and a top-class user of magic. However, you're not exactly a specialist in reasoning arts, are you?"

"My, but I did raise you to be a first-class botanist, didn't I?"

"Of course, and I'm deeply grateful and respectful for that. That's precisely why I'm challenging you. Can you understand what this reasoning formula - devised by 14-year-old Navi - represents?"

This is interesting. A disciple, along with his own disciple, challenging the master. Quite the entertainer, isn't he?

Roze, as if accepting the challenge, stares intently at the diagrams. After taking her time to look through all the papers, Roze exhaled and said:

"...I give up. I can tell it's some kind of output device that includes thermal conductivity. But beyond that, I'm completely lost."

"I see. As expected, reasoning arts are your only weakness, teacher."

"Why do you look so happy about that?"

"Hehe, of course I'm happy to see a new side of someone I love."

"You haven't changed at all."

"Well, I am an elf. It's in our nature not to change easily."

Prennarec laughed while weaving sweet words. It's clear to both of them and to me listening that this wasn't meant in a romantic sense. It was the ultimate expression of affection built between two people with a long history together. What a nice relationship.

While these two were chatting, I looked at the formulas on the diagrams and spoke to the girl sitting across from me.

"Navi-san. May I ask you something?"

"Eh... u-um... y-yes!"

Hmm, she's really bad at communication. But that's what's good about her. No, wait, that's not the point!

"This second diagram, I think it's about the decompression mechanism, but with this calculation, wouldn't this part be under too much strain? I think it would break unless the material is at least as strong as mithril."

"Eh, you... you understand this?"

Navi exclaimed in surprise. Roze and Prennarec stopped their conversation and looked our way.

"Yes. This is a diagram for a pressure cooker that raises the boiling point by creating a high-pressure state inside a sealed container, right?"

"T-That's... right."

Navi nodded vigorously. I thought so. This means it could be a treasure for me too.

After all, even in Stoania, the forefront of reasoning devices, pressure cookers haven't been researched. Stoania is a great nation in reasoning arts, but they didn't really have the idea of applying cutting-edge technology to cooking. I thought they would have developed more since they have abundant food thanks to the dungeon, but unfortunately, I couldn't find any good cooking utensils.

However, here we have an apprentice servant with talent in reasoning arts! If we cooperate here, I have a feeling we can get a pressure cooker sooner rather than later. I lean forward and start talking rapidly.

"I think it's also related to the steam released without pressure adjustment, but with this formula, I assume Navi-san is considering the normal boiling point of 100 degrees, but the internal temperature of the cooking device will be higher than that. Of course, if you use materials weak to heat, it will break, and even if it's heat-resistant, if the metal has low hardness, I think the number of uses will be quite limited. I think the decompression device needs to be done in stages, and there should be a mechanism that automatically adjusts when a certain value is exceeded."

"T-That kind of... how?"

"Well, I think it's possible just by preparing a hole with a spherical weight. If the pressure increases, the weight will lift and air will escape, and as it does, the weight will lower again and close the lid... essentially a pressure regulating valve."

"I-I see... that might... work..."

"Right? If we do that, this part designed for the load during discharge would become completely unnecessary, and we could make it lighter. It would reduce costs, and more importantly, being lighter would reduce the burden on the user—"

As Ruruk and Navi were engrossed in conversation like this, the two adults:

"T-Teacher... is this child a reasoning artist?"

"No, his reasoning proficiency isn't even 1000 yet. But sometimes he comes up with ideas like this that surpass his proficiency. It's like he doesn't know the intermediate formulas but somehow knows the correct answer from the start, taking such shortcuts. It's the same with mystic arts, he keeps creating new formulas like this. And he does it without any consideration for the dangers... that's why he's a problem child."

"I see. Seems like quite a difficult child."

"It's really exhausting."

The master and disciple talked face to face, but they didn't seem inclined to stop us as we continued our excited discussion. Ruruk and Navi kept staring at the pressure cooker design and exchanging ideas even after the sun had set.

Incidentally, for some reason, Elen was in a bad mood and took it out on me before going to bed.