The investigation team from the Kingdom of Egerea was currently camping at the Soldrake Ruins, located further east of the Botzfa Ruins.
The captain of the team was Paul Raid. In the past, he had narrowly escaped being overrun by a swarm of Giga Ants that had emerged from deep underground after he attempted to remove a golem guarding a different set of ruins.
"It was a nightmare," he muttered.
Even now, the mere memory made his skin crawl.
Though they had used Collapse to block the entrance back then, there was no telling when the creatures might emerge again. However, since not a single one had appeared in all the time since, he assumed the danger had largely passed.
One of the objectives for this investigation was to confirm that no such threats remained. To ensure they could escape into the sky at a moment's notice should the Giga Ants reappear, they had set up their camp directly alongside their airship.
Fortunately, their caution seemed to be unnecessary. No matter how much their earth-attribute magic users searched, they could find nothing resembling a nest beneath the surface.
On Hourai Island, Laojun was monitoring the various investigation teams using the Peeping Telescope.
"They are taking proper precautions against potential threats. This should be fine... though we have already exterminated the Giga Ants in that area."
When Jin had previously inspected the ruins, he had left markers behind. Even with the entrances sealed, it hadn't hindered Hourai Island’s cleanup operations; as a result, the hundreds of eggs left behind by the ants had all been destroyed.
"We have also managed to stockpile a significant amount of the formic acid secreted by the Giga Ants, and our analysis of it is proceeding well."
This was the same potent acid that had once managed to corrode the skin of Reiko, even though her exterior was reinforced with the wing membranes of a Sea Dragon.
Through the collaborative efforts of Saki and Laojun, the secret of the acid had been revealed: it possessed a magical effect that severed molecular bonds held by free ether. In essence, it was a liquid imbued with the property of Dissolute.
The ability to biologically synthesize such a substance was a testament to the Giga Ant's status as a formidable magical beast. Now, however, Hourai Island was capable of synthesizing a substance of equal or even greater potency.
Just then, the door to the room opened.
"Laojun, I've just about finished the analysis on the magi-mercury."
Saki Eschenbach wandered in from the laboratory, looking a bit weary but satisfied.
"You have done excellent work, Saki-sama."
"Kufu, I appreciate the praise, but more than half the credit goes to you, Laojun."
Saki had become a top-tier alchemist in her own right, her talents particularly well-suited for material analysis.
"Oh, are those the investigation teams?" she asked, glancing at the monitors.
"Yes. At present, we are tracking teams from the Kingdom of Egerea and the Klein Kingdom. Tomorrow, teams from the Kingdom of Elias and the Celuroa Kingdom are expected to depart as well."
"What about the Kingdom of Franz?"
"Since their internal affairs have not yet fully stabilized, they have declined to send a team, choosing instead to focus on providing logistical backup."
"I see. And what about Nostalgia?"
"I plan to observe them next. After all, Elena herself is heading the expedition personally."
"Heh. That’s interesting. Should I go grab Jin and Elsa?"
"That will not be necessary. I informed My Lord just a moment ago. He should be arriving shortly."
"You're as efficient as ever, Laojun."
"I aim to please."
Just as Laojun spoke, Jin and Elsa Randol arrived from Kaina Village, accompanied, as always, by Reiko.
"Laojun, I heard Nostalgia has started their investigation of the Former Leonard Kingdom as well?"
"Yes, My Lord. It appears they have just arrived at the former capital, Diaa."
Laojun adjusted the magi-screen to display an airship of a design unique to the Nostalgia faction.
"So, that is Diaa, the old capital."
The Golden Princess, Elena, spoke as she looked out over the ruins.
"So it seems. But it's remarkably overgrown. I wonder just how many years have passed for it to end up like this."
The man agreeing with her was the number two of Nostalgia, Donald Callow. He was a highly skilled magi craftsman.
"The capital of Diaa is situated quite far south within the borders of the Former Leonard Kingdom, meaning many of the plants here don't wither even in the winter. It’s likely the climate allowed the vegetation to reclaim the city much faster than one might expect."
"That makes sense." Donald nodded at Elena's assessment.
"Where shall we set down?" the pilot asked.
From their vantage point, the sea of grass stretching out below seemed to offer no clear landing site.
"Let’s see... there appears to be a wide riverbank along that river to the south. Let's aim for that."
"Understood."
The Nostalgia airship slowly banked toward the south.
They found a broad riverbank where the grass grew thin enough to allow for a landing. Picking a flat area roughly the size of a ball field away from the water's edge, the airship touched down gently.
"Any signs of magical beasts?"
"No reactions detected."
Nostalgia utilized magi-devices sensitive to magical signatures, capable of detecting threats within a five-hundred-meter radius. While they couldn't pinpoint a specific direction or intensity—making them useful only for early warnings—they were invaluable for securing a campsite.
"Then we'll camp here for the night. We'll start the survey tomorrow."
"Understood."
Aside from Donald, Elena's only companions were the pilot and a single guard. The soldier quickly set about preparing the camp. Because their numbers were small and they possessed many convenient magi-devices, the work was light.
Since the team was so small, they had been able to carry an abundance of high-quality provisions, allowing them to enjoy a surprisingly good meal. Donald, the pilot, and the soldier were all able to drift off to sleep satisfied. With their detection devices and Elena herself on watch, they felt perfectly secure against the local wildlife.
The following morning, as soon as the sun rose, they began their archaeological survey.
"This is..."
"Such incredible craftsmanship."
Elena and Donald took the lead in the investigation while the guard maintained a perimeter watch.
"Oho, this architectural style is fascinating."
"There is no doubt about it—ancient technology is still preserved here."
The voices of the two were bright with excitement as they worked.
(They certainly have good instincts,) Laojun thought to himself.
At the moment, Jin, Elsa, and Saki had all returned to their own projects, leaving only Laojun to monitor the progress of the investigation teams.
Through previous surveys conducted by Hourai Island’s forces, most of the significant dangers in the area had already been neutralized. However, the ruins themselves had been left largely untouched, allowing the people of this world the chance to discover and analyze them on their own.
In fact, Laojun believed it was for the best. So long as they didn't stumble upon anything truly catastrophic, like the forbidden relics of the Great Magic War, their progress was more than welcome.
The Klein Kingdom, the Kingdom of Egerea, and Nostalgia—all three teams were beginning to produce meaningful results in their respective search areas.
Backtracking to the previous day...
Jin and Elsa were deep in discussion with Saki.
"It’s just as I suspected. This magi-mercury seems to have a gentle but incredibly firm molecular bond due to the free ether it contains," Saki explained. "As a result, while its melting point is only five degrees different from regular mercury, its boiling point is over two hundred and fifty degrees higher. It’s practically a different element."
"I see..." Jin murmured.
"There's more. Its reactivity is abnormally low. It’s staggering that it doesn't form dangerous compounds like dimethylmercury."
"Heh."
Knowledge regarding such chemical compounds and their toxic effects on the human body had come not from Jin’s own world, but from the scientific texts brought to this world by the Magus, Shuuki Tsetse.
"Physically, it’s almost identical to regular mercury in every other way—mass, expansion rate, viscosity, and so on."
"It’s strange that the expansion rate remains the same even though the boiling point has increased so much," Jin noted.
"Yeah. It's likely the free ether acts as a sort of tether, holding the mercury atoms—or molecules?—together even as they try to transition into a gaseous state."
"Man, the physical properties of free ether are still such a mystery..."
"...In that case, is it possible to swap out the contents of our mercury thermometers?" Elsa asked.
Saki gave a knowing smile at the question.
"Kufu, I figured you'd ask that. The answer is yes."
This was excellent news. If they could replace a hazardous substance with one that had significantly lower toxicity and risk, Jin was all for it. He immediately sent instructions to the Smith golems.
Within a few days, every drop of mercury used on the island would be replaced with magi-mercury. Since its primary use was in thermometers anyway, the transition would be simple.
"Now I just need to look into the possibilities of using this for a Fluid Form Drive."
Jin seemed more interested in the engineering applications.
"Though, the weight is an issue."
The specific gravity of mercury is approximately 13.6 at 0 degrees Celsius. While lighter than adamantite, it was significantly heavier than iron or copper.
"I'll have to run some tests on the relationship between volume and power output."
"Jin-nii, you should also investigate the toxicity as thoroughly as possible."
Jin nodded at Elsa’s cautious advice.
"You're right. I'll make sure to let the golems handle the actual handling for the experiments. Thanks, Elsa."
"Mm. Please do."
"Kufu, you two certainly make a good pair," Saki teased, watching the couple look out for one another.