On January 29, the day after celebrating Martha’s birthday, Jin, Elsa, and Reiko returned to Miyako with nonchalant expressions.
The official story was that they had spent the previous day holed up in the Guest House, engrossed in the library’s collection. In reality, their two body doubles—their Doppels—had already finished reading almost the entire, staggering collection of books. Naturally, that information had already been stored within Laojun’s memory banks.
"Jin-sama, Elsa-sama, Reinhard-sama, what would you like to do today?" Mii, acting as their host, came to inquire after breakfast.
"Let’s see... You’re currently working on a waterway, right? I think I’d like to go observe that."
Jin himself had very little formal knowledge of civil engineering. Most of what they did on Hourai Island was accomplished through sheer magical force. He wanted to take this opportunity to absorb whatever knowledge he could.
"I understand. I’ll make the arrangements," Mii said with a nod. She stepped out of the room for a moment and returned shortly after. "The site supervisor happened to be at the town office, so I’ve already spoken with him. He said it would be an honor to have the Magi Craft Meister observe the site."
"I-I see."
As usual, Jin felt a bit awkward being put on a pedestal, but he didn't let his discomfort show to Mii after she had gone to the trouble of setting it all up.
"Shall we head out now, then?"
"That sounds like a good idea."
Since they had no other plans, Jin and the others decided to head to the construction site immediately.
"...This is a peculiar vehicle," Reinhard remarked honestly as he climbed into his own rickshaw. "I wonder why they don't just have golems pull these instead?"
Jin, riding in the adjacent rickshaw, responded to the murmur. "If you did that, you’d have to reinforce the frame significantly, or it would be dangerous."
"Ah... true enough."
With that one comment from Jin, Reinhard recognized the risk. It was fine now because they were moving at a human’s running pace, but if a golem pulled it, the vehicle could easily reach fifty kilometers per hour. If a fragile chassis like a rickshaw were to overturn at that speed, the results would be disastrous.
"You could also use a golem with a low output," Jin suggested. "If it's dangerous, you just apply a limiter."
"I see. They have the power and the stamina. There might actually be a demand for that."
While exchanging such ideas, they reached the outskirts of town. They had arrived at the exact spot where the waterway was being cut into the center of Miyako.
"Oh, this is impressive!" Reinhard exclaimed in admiration.
And for good reason—the construction was being carried out entirely through manual labor.
"Welcome, Mr. Diplomat, and Mr. Magi Craft Meister." A man who appeared to be the site supervisor came forward to greet them.
"Duza-san, thank you for having us," Mii said. The supervisor’s name was apparently Duza.
"I’ll give you a brief explanation. First, we dig the channel, and once it's finished, we let the water flow. However, there are several things we have to be very careful about during the process."
"I see."
He explained that the two points they prioritized most were preventing the channel from collapsing and ensuring there were no water leaks.
"Certainly, if those aren't guaranteed, it won't function as a waterway," Jin replied.
Duza smiled broadly. "There is one more requirement that is quite difficult to manage. Can you guess what it is?"
His tone was slightly challenging, so Jin took a moment to think it through seriously.
Let's see... the most important things for laying a waterway...
Jin thought back to the time he had piped the hot spring water to Kaina Village. The work itself had been done with Craft Magic, but the fundamental principles should be the same. Then, it hit him.
"Would it be the gradient of the waterway?"
If the slope wasn't calculated correctly during construction, the water wouldn't flow in, or it might flow backward or stagnate. It simply wouldn't serve its purpose.
"Correct! As expected of the Magi Craft Meister." Duza seemed a little surprised by how quickly Jin had found the answer.
The group moved slightly closer toward Lake Sayama, arriving at the section currently being excavated.
"There are many layers of stone around here, so this is a spot where we’re struggling to dig," Duza explained while showing them the progress.
Indeed, stones larger than watermelons were being unearthed one after another.
"The stones we dig out are processed and used to line the walls and bottom of the channel for reinforcement."
"So you don't let anything go to waste."
The reason, Duza explained, was that it was inefficient to transport heavy stones a long distance just to discard them. It was a very rational approach. However, the actual processing of the stone was done manually using hammers and chisels.
It’s like the Edo period, Jin thought. But perhaps this was simply the Mitsuho style. He wondered idly if such labor would eventually be handled by golems as exchange with the Allied Kingdoms progressed, all while the rhythmic sound of chisels carving stone filled the air.
Just then, a loud voice called out from the trench.
"Supervisor!"
"What is it?"
"We've hit a massive stone, sir!"
"No, this is more like a boulder!"
Jin and the others peered into the site together. There, partially unearthed and blocking the path of the waterway, was a truly massive rock.
"...It looks like chert," Jin muttered. It was a dense, hard rock, the same kind used in the Hourai Island laboratory.
"This is going to be a real headache," Duza said, his expression darkening.
Mii turned to Jin with a curious look. "Jin-sama, what do people in the Western countries do at a time like this?"
"There are a few methods. Usually, they involve magic."
"For example?"
"Splitting it with Craft Magic, or having a golem unearth it..."
"I could simply shatter it," Reiko interjected from the side.
Jin gave a wry smile. "That’s true, but that’s hardly the standard approach."
Hearing that, Duza turned to face Jin. "Jin-sama, is that true?"
"Eh?"
"That you can shatter that rock."
"It would be simple," Reiko answered in Jin’s stead. "Shall I do it?"
"By all means, please!"
"I understand. Father, would that be acceptable?"
"Yeah, since they’ve asked for the help. But keep it moderate."
"Yes."
Reiko jumped down into the construction site. "Everyone, please step back. It’s dangerous."
"What?"
"A-Ah, you’re the Magi Craft Meister’s attendant. We’re counting on you!"
One of the laborers recognized Reiko, and the workers all evacuated the trench in a great hurry.
"Here I go," Reiko said.
She unleashed a light strike.