April 25th was the day Jin D and Reiko returned.
After resting for a day on Hourai Island, Jin visited the Nord Federation to recount the series of events to Sion.
"I see, it sounds like you had quite a struggle. Good work, Jin."
Upon learning that Jin had been caught up in more trouble than she had expected, Sion offered words of appreciation.
"Actually, I wanted to ask you something, Sion."
"...About those bandit golems?"
"Yeah. Do you know anything?"
"Well... Marikka might know more than I do. Let's call her."
They reached out via manacam, and Marikka arrived in a hurry.
"Welcome back, Jin-sama."
"Hey, Marikka. Right to the point..."
Jin explained the golems he had encountered in Blue Land.
"Golems that are neither Adriana-style nor ball-joint style, you say?"
"Yeah. Do you know anything?"
"Yes. A little, at least..."
With that preface, Marikka began to speak in a quiet, measured tone.
"First, as a premise, the Fluid Form Drive ultimately never became the mainstream technology. It was simply too heavy."
Because it used magi-mercury—a magi-isotope of mercury—the specific gravity was approximately 13.5. Since it required metal armor to serve as both the container and the exterior, a golem the size of an adult male would weigh as much as 900 kilograms.
If you added the weight of its weapons, it would come to nearly one ton. That was equivalent to the weight of thirteen human soldiers. It was simply too heavy for practical use. Furthermore, transporting such units by airship was extremely difficult.
"I get that. But magi-rock and magi-resin can't produce the same power as magi-mercury, can they?"
"Exactly. That is why I felt the establishment of the ball-joint style was such a major turning point."
While the ball-joint style certainly contributed to lowering costs, it was inferior to the Adriana-style in terms of visual grace and durability in extreme situations.
"It could not be used for lifelike automata," Marikka said, her voice filled with deep emotion as she reminisced. "Widespread adoption of golems and automata as a labor force was a goal for countries all over the world. However, the cost-effectiveness was low, and things did not go as planned."
"I see."
It might be easier to understand if compared to the spread of private automobiles in Jin's original world. In the Showa 30s, private cars had hardly reached general households. However, during the period of rapid economic growth following the Tokyo Olympics and the development of the Metropolitan Expressway, they began to spread as a status symbol. Then, after the oil shock, they became common household items in the Showa 50s, eventually becoming a standard part of life during the bubble economy of the Showa 60s.
Additionally, in the dawning era of the automobile, the "Automobile King" Henry Ford introduced a revolutionary model called the Model T. Through mass production on an assembly line, he reduced the price from a high of 950 dollars to a low of 290 dollars.
But back to the matter at hand.
Much like with automobiles, there was once a group of engineers who believed that the cost of golems could be reduced through mass production.
"They were relatives of the Jin Family," Marikka explained. "Since they were not of the direct line, they would not have known about the existence of Hourai Island. However, there was someone who had thoroughly studied the literature in the archives of Jin Castle in Kaina Village and the mansion in Loizart within the Empire."
"Oh?"
"I do not know their name. At the time, I was focusing on the education of the younger generation in the Nord Federation."
"I see... Well, that's fine. So this relative—or perhaps a descendant—of the Jin Family developed a new style?"
"It seems that is the only possibility."
Jin voiced the doubt that immediately came to mind.
"Hmm... Then why didn't it become widespread?...Wait, could it be..."
Midway through his sentence, the reason occurred to him.
"Yes, it was because of the Magic Federation and Markitus."
"I thought so."
Following that, Marikka had eventually isolated the direct descendants of the Jin Family on Onogoro Island.
"I see. I understand the gist of it now. Thanks."
"I am glad to have been of help-sh."
Marikka tripped over her words at the very end.
After taking a breather, Jin continued his conversation with Sion and Marikka.
"If that's the case, then the bandit group must have found golems made by that engineer."
"That seems likely," Sion agreed.
Duke Blue would likely interrogate the bandits and reveal the location of their source.
"I'm interested in that place. I wonder where it is?"
It was Sion who answered what was essentially a question to himself.
"Why don't you just ask Duke Blue? You could probably go with them."
"I suppose you're right."
As far as Jin was concerned, he wanted this technology to be shared with the world. He felt it would be best if someone in an official position found the technical legacy and put it to use for the good of society. Regardless of those grander goals, Jin simply wanted to see the legacy with his own eyes.
"I'd like to at least take a look ahead of time..."
At that moment, Reiko, who had been silent until then, spoke up.
"Father, it seems Laojun already knows where it is. To be precise, he has been monitoring the interrogation at Duke Blue's mansion using a Peeper."
Therefore, he was already aware of the contents of the bandits' confession.
"Oh, really? So, where is it?"
"Yes. It is in Futorks, in the Liebus Region of the eastern Celuroa Kingdom."
"I see. That was near the border with the Klein Kingdom, wasn't it?"
"Yes. There is a fort nearby."
"Father, that place is..."
Reiko began to explain the history of research facilities in the region. At the time, various countries established research laboratories in remote areas to conduct their work. They were not placed in central areas simply because there was no space for the large-scale experiments and field tests required for such projects.
As for transportation, they utilized magic circles and airships. In Futorks, there was a fort built during the era of conflict with the Klein Kingdom; the researchers had renovated it into a facility.
"In that case, it would have been spacious, the buildings would have been sturdy, and there would have been living quarters—it must have had everything they needed."
Jin imagined that it would have been quite practical to use.
"There must have been some very motivated researchers there."
Jin tried to imagine the bustle of the facility in its prime. He decided he might as well go and check it out for the time being. Since some paperwork would be required to travel from the Kingdom of Egerea to the Celuroa Kingdom, Jin calculated that he would have about two or three days to spare.
"What will you two do, Sion, Marikka?"
"I'll pass," Sion replied.
"I... I think I'll decline as well," Marikka added.
Since both of them chose to stay behind, Jin and Reiko returned to Hourai Island together.