"...Back then, I was working so hard just to secure my foothold."
Jin began to speak once more.
＊ ＊ ＊
The standing of Jin’s group—Jin, Eira Shiata, and Kachea—in Rofon was solidifying by the day.
The first factor was the improvement in the residents' lives thanks to the repairs made to the mana stands, which served as the town’s primary infrastructure.
After all, the amount of mana provided for a single copper coin—one Toll—had ultimately increased fivefold. This meant the unit price had effectively plummeted to a fifth of its original cost. This was largely due to a complete overhaul of the internal sequences using magic circles.
Then, there was the maintenance of the Golem cars.
Paerova Sondvik had twenty-three old Golem cars in his possession. He had apparently acquired them all at bargain prices because they had broken down, but Jin, Eira, and Kachea’s "team" had restored them.
Furthermore, they did so using magic circles instead of magi-crystals. Unlike the control cores of Golems themselves, which required high reaction and processing speeds, Golem cars were perfectly practical as long as their response time was roughly equal to—or even slightly slower than—a human’s.
＊ ＊ ＊
"Well, well, this is yet another pleasant surprise."
Paerova Sondvik drained his wine in high spirits.
"Not just Jin, but even Eira has actually produced results. She’s formed a team with Jin and Kachea now."
"Indeed. I thought she was just a drain on our resources, but it seems she can really shine under the right guidance."
"Umu. That magi named Jin looks unreliable at first glance, but his depths are unfathomable. Make absolutely sure he is not treated crudely."
"Yes, I understand."
"That girl Kachea was quite a find as well. I thought she might serve as leverage against Jin, but she has proven to be exceptionally competent."
"Quite so."
"...And what are they up to now?"
"Yes, it seems they are working on some kind of new magi-device or Magi Machine."
"I see. I look forward to it."
＊ ＊ ＊
"Hmm, it really is difficult without proper materials."
"Jin-san, do you really think we can do it...?"
"Jin, what's this for anyway?"
What Jin was trying to create was a Jet Thruster—or rather, a simplified version of one.
"It’s something that uses wind-attribute magic to generate propulsion."
"C-Can you really do something like that?"
"It’s possible. Eira, can you use 'Wind'?"
"Yeah, at least that much."
"We'll be applying that."
"But what could you possibly move with that?!"
Eira argued that it couldn't possibly match the performance of a Golem car. She was correct. However, Jin had another goal in mind.
"A boat."
"A boat?!...I see, a boat... but..."
"But?"
"Building boats is regulated, isn't it?"
In the Mercana Principality, individuals were forbidden from owning boats exceeding five meters in length, four meters in width, or three meters in height.
"They're only used for catching fish near the shore anyway. Besides, there are stories about magical beasts out in the open sea."
"Magical beasts?"
That was news to Jin.
"I thought there weren't any magical beasts on this continent?"
"I-I heard that too," Kachea added.
But Eira shook her head.
"Not on the land. But they're in the sea. I believe they're called 'Death Sea Serpents'? They’re supposedly giant sea serpents."
"Death Sea Serpents... those are definitely magical beasts."
"Jin-san, do you know about them?"
"...Ah, yeah. It seems so... I think..." Jin feigned that the memory had just surfaced.
"Heh, did another memory come back to you? So, what kind of creatures are these Death Sea Serpents?"
"Let’s see, they grow to over ten meters long and are ferocious carnivorous magical beasts."
"Over ten meters... that’s incredible. Or rather, terrifying," Kachea said.
"The stories say they're in the waters north of here. That’s why nobody wants to go out to sea in a boat."
"Hmm..."
Yet another fact had come to light, but Jin couldn't exactly celebrate.
I thought I could gradually build larger ships and eventually cross back over to the Lauren Continent...
Disappointed, Jin realized that this plan might be reckless.
"But the technology can still be applied elsewhere."
If they could travel upriver, it would be a massive help for logistics, Jin reasoned.
"I believe this kind of propulsion system is used."
Jin drew a diagram on a piece of paper to show them.
"Hmm? Is the intake over here? It’s quite wide."
"Is the outlet... over here? Why is it so narrow?"
"That’s the clever part. Look, when you blow air out of your mouth, you can blow harder if you narrow your lips, right?"
"Oh, you're right."
"I see!"
Once the two were convinced, Jin explained that a propulsion system like this could likely be made using magic circles.
"True. It doesn't need precise control, and it wouldn't be much of a problem even if the reaction time is a bit slow."
"Exactly."
Thus, Jin and the others began working to develop "vessels to travel the rivers."
"Is bronze okay for the main body of the propulsion system?"
"Iron rusts easily, so bronze sounds good, doesn't it?"
"We only have about twenty-two kilograms of bronze available right now," Kachea noted, "so please keep the prototype under ten kilograms."
With Jin leading the work, the prototype was completed in a single day. Since it was a simplified version of a Jet Thruster, he named it the "Air Jet."
"Wake up."
"O-Oh! It really is generating propulsion."
Holding the prototype propulsion system in her hands, Eira felt the reality that this could actually work.
"Jin, you're amazing. You must have done this kind of work before."
"Hmm, probably... I guess so."
Jin gave another vague reply.
"Hmph, same as always. Well, whatever. I'm already looking forward to seeing the look on Paerova’s face when we show him this."
And that night.
"T-This is incredible!"
Paerova Sondvik’s shout rang through the air.