“In the ‘mana linkage’... of the ‘control system’? What role... does the ‘active core’ play?”
“Huh?”
Jin was dumbfounded.
At first glance, it seemed like a difficult question, but since an ‘active core’ is simply the component that triggers an effect within a complex system, its relevance to a ‘mana linkage’ was negligible.
When he relayed that fact exactly as it was, the administrator took some notes and spoke again.
“Then, please explain the ‘magi-sequence’... in a ‘mana generator’?”
“Uh, well...”
A ‘mana generator’ was a primitive form of an ether converter. Naturally, Jin understood its structure perfectly.
“By targeting the free ether existing in space with ‘ether waves’ equivalent to weak mental waves, you can draw it in. For that purpose...”
Jin rattled off his explanation like clockwork, but the administrator simply took notes with a bewildered expression that suggested he didn't understand a single word.
“W-Well then, that concludes the session.”
The administrator closed his notebook and hurried out of the room.
“...That guy definitely didn't understand a thing he was asking. Especially with the questions for Jin—it looked like he was just reading off a script.”
Eira muttered indignantly.
“That was probably the point of the consultation. There might have been someone else listening to this exchange from elsewhere.”
Eira seemed convinced by Jin’s suggestion.
“I see. That’s a roundabout way of doing things.”
For the next two full days, there was no word from the authorities, so the three of them obtained permission to enjoy some sightseeing in the royal capital.
“The selection of goods really is on another level, isn’t it?”
“It certainly is.”
“Hey, Jin! Look at this, it’s incredible!”
On the first day, they had spent their time looking at fashion, which left Jin exhausted and Eira and Kachea with significantly lighter purses. On the second day, they decided to stick to window shopping, though they still intended to buy anything they truly liked.
“Let’s see... Huh, this is...”
The three of them, mostly browsing tool shops and magi-device shops, had arrived at a shopping district on the main street.
“It’s an automata, though it looks pretty old. I kind of want it, but the price...”
The displayed price was 3.5 million Toll—roughly 35 million yen.
“Who would even buy that...?”
“Isn’t it mostly just a showpiece?” Jin added.
He couldn't feel even a trace of mana flowing through it, so he secretly used ‘Analyze’. The ether converter was damaged, and the mana driver was missing entirely.
It was likely just a decorative piece or something kept for collectors, Jin imagined.
“Jin-san, what is this?”
Kachea pointed to a magi-device displayed in another shop.
“Let’s see... Oh, there’s something interesting. This is a magi-lamp... or rather, a magi-lamp stand. The design is quite—”
As Jin spoke, a character that looked like a stylized ‘B’ caught his eye.
“‘Beena’...?”
“Eh?”
“N-No, it’s nothing. It just occurred to me that an acquaintance might have made it, that’s all.”
Flustered, Jin spoke the truth almost instinctively.
(Still, considering four hundred years have passed, it might be a brand from a workshop Beena established...)
“Jin?”
“...Ah, what is it?”
“You were spacing out, so I wondered if something was wrong.”
“I was just thinking about something.”
“...Does it have something to do with that name, Beena?”
“Maybe, maybe not.”
“What kind of answer is that?”
Eira gave a wry smile and didn't press him further.
“Oh, this might be good.”
“This is intriguing.”
“It’s a bit expensive, though...”
They continued browsing the shops of the royal capital until dusk.
“Hmm, so the knowledge of this magi named Jin is indeed peerless?”
“Yes. To the point that it would be a waste to leave him in this country.”
“I see. I am currently inquiring with the home country. A reply should arrive shortly. Once it does...”
“How can we reduce friction and wear on sliding parts?”
On the third day, the group had begun a voluntary study session.
“If you rub a hard object and a soft object together, naturally the soft one will wear down.”
“That’s obvious,” Eira affirmed.
“Then, what about objects of the same hardness?”
“...Do both of them wear down?” Kachea asked.
“Correct, Kachea.”
Jin continued to explain the theory.
“As a side note, ease of wear isn't determined by hardness alone.”
“What do you mean?”
“Wear happens because the material is being ‘shaved away,’ so if the bonding force between molecules is strong, it’s harder to wear down. However, that isn't exactly the same thing as ‘hardness.’”
“Hmm, I think I get it, but I also don’t.”
Eira tilted her head in confusion.
“Th-Then, what exactly is ‘hardness’?” Kachea followed up.
“It’s the resistance of an object to deformation and its resistance to being scratched. Resistance to deformation depends not only on bonding force but also on molecular structure, and resistance to being scratched is the very definition of hardness.”
Kachea looked just as conflicted as Eira. It was no wonder, since even basic physics wasn't common knowledge in this world.
“Look, there are stones that are hard but easy to wear down, right?”
“Ah, come to think of it, there are.”
“That’s a classic example of high hardness but low wear resistance.”
“...When you put it that way, I think I understand.”
“Adamantite has high hardness, is resistant to deformation, and has high wear resistance, which is why we apply a thin coating to things like golem joints,” Jin explained.
“Then it seems like it could be used for bearings too!” Eira exclaimed.
“That’s right. It also prevents seizing. It’s just expensive.”
“Ah, cost-effectiveness, right?”
Kachea nodded, satisfied with that reasoning.
Jin thought to himself that these two were talents far too good to be left in their current environment.
However, Jin himself was currently a wanderer, still searching for a way home. While he wanted to return to Elsa and the others as soon as possible, he also found himself worrying about the future of the women he had met here.
It was a troublesome problem, and his worries were far from over.