While Hanna and Jin enjoyed their fishing trip, a separate development was unfolding elsewhere.
It took place at the Elrad Mine, where Laojun had been conducting a meticulous investigation.
The upper reaches of the Elrad Mine functioned as a standard mine, yielding iron, copper, tin, zinc, lead, and trace amounts of adamantite. Deeper strata produced gemstones, magi-stones, and magi-crystals. Because Elradrite was occasionally discovered even further down, the site had been named the Elrad Mine.
"It seems this is not a pegmatite formation," Laojun noted.
He gathered geological data while slowly continuing boring operations with the Mini-Moles. Pegmatite, also known as giant-grained granite, forms when magma cools and solidifies slowly deep underground. During that process, various minerals crystallize at different rates due to their varying melting points. The Inado Mine and the areas beneath Hourai Island belonged to pegmatite deposits.
The Elrad Mine was different; it was a "skarn deposit." In simple terms, this is a mineral deposit formed when high-temperature plutonic rock, such as granite rising from the depths, undergoes a chemical reaction with rocks like limestone or dolomite, causing metallic elements to concentrate.
The Mini-Moles had been deployed to the Elrad Mine on March 4th. This followed the discovery that a mysterious Warp Gate located beneath the Detached Palace in Dali connected to the depths of this very mine. After gathering geological data in the shallower, known sections of the mine, the Mini-Moles dove even deeper into the earth.
"One thousand meters from the surface... and the temperature isn't as high as expected."
Given the high elevation of the surface, they were likely still above sea level even at this depth, but Laojun still found the unusually gradual rise in geothermal temperature suspicious.
The three Mini-Moles—each ten centimeters in diameter and thirty centimeters long—drilled forward at a rate of six hundred meters per day. Then, in the early morning of March 6th, Mini-Mole 3 discovered an underground cavity.
On board for such an event were ultra-miniature golems designated as Command units. Command 3 exited the Mini-Mole to begin a reconnaissance mission. Since the Command units possessed performance capabilities equivalent to the Shinobi Squad, they could gather information undetected even if humans were present.
After an hour of investigation, Command 3 reported back. Based on the findings, Laojun concluded that the cavity resembled catacombs. He relayed this information to Jin that same morning. Since the catacombs appeared to be nothing more than a hollow space, the Mini-Moles continued their descent deeper into the earth.
Then, on the morning of March 9th.
"A report from the Mini-Mole?...Hmm, a mysterious barrier underground. It is truly a 'mystery' indeed. Now, how shall we proceed?"
Laojun paused to think for a duration that was unusually long for him—though it only lasted a few seconds.
"Slow the advance speed and proceed with extreme caution. In the event of an emergency, Command 1, 2, and 3 are to abandon the Mini-Moles and escape via the transporters. The Mini-Moles themselves are to self-destruct."
He issued instructions that prioritized the investigation above all else. As ordered, the Mini-Moles slowed to one-twentieth of their original speed and continued drilling. Along the way, they transmitted various data back to Laojun.
Among the findings was a startling discovery.
"Oho, it seems the free ether concentration is rising."
Compared to the surface, the free ether concentration had increased by fifty percent. While not as high as the levels found in the demon territory, it was close to the concentration found near the Pazdext Great Isthmus.
"I wonder if there is a singularity, or if the mysterious barrier is responsible. Perhaps there is some other reason entirely. Regardless, the necessity for a thorough investigation has only increased."
The Mini-Moles pushed further down. They were now approaching a depth of three thousand meters. Suddenly, Mini-Mole 2's Sonar detected an open space just a few centimeters ahead. It immediately reported to Laojun and requested further instructions.
"Hmm, another cavity. And this one is inside the mysterious barrier."
Laojun felt they were finally reaching the heart of the matter. The reaction from the marker secretly sent through the Warp Gate in Dali was also in this vicinity. Regretting that he could not investigate in person, Laojun issued his next order.
"Proceed with even greater caution."
After advancing another three centimeters, they struck a metallic wall rather than rock.
"Metal... clearly man-made. An artificial space this deep underground?"
The mystery deepened. To solve it, they would have to find a way past that metal wall.
"Even as small as the Mini-Moles are, they are still ten centimeters wide. It would be impossible to go unnoticed once inside."
Laojun reflected that he should have equipped the Mini-Moles with Invisible capabilities. While he could use the built-in transporters to return them to Hourai Island via Shinkai, it would take a significant amount of time to get them back to this exact location. Sending them back down via a transporter was also out of the question; even with Laojun's control, he couldn't achieve the millimeter-level precision required to place them back in the exact same spot.
"There is no choice but to proceed as we are."
Since they were drilling using a teleportation method, their greatest advantage was that no debris was produced. However, leaving a hole would risk their intrusion being discovered, so they decided to process the metal section into a lid-like shape that could be refitted. The Command golems, built to repair and maintain the Mini-Moles, were capable of performing that level of Craft Magic.
Finally, Mini-Mole 2 breached the metal wall and entered the cavity. It simultaneously deployed a force generator to prevent itself from falling. The hole was immediately sealed with the makeshift lid. The Mini-Mole was equipped with a magic eye, allowing Laojun to view the interior of the cavity in real-time.
"This is..."
He saw a neatly arranged room. It felt familiar.
"It looks remarkably like the Heavenly Ship."
It resembled the Negadoll base that Laojun's mobile terminal, Laozi, had once infiltrated within the demon territory. Watching the footage transmitted by Mini-Mole 2, Laojun grew certain. There were no people in sight. The room was sparsely furnished, giving it the feel of a vacant chamber, but the atmosphere it projected was unmistakable.
"This place, like the other, must be a site related to the Origin."
Laojun judged that there was at least some kind of connection between the two.
"Install a marker on the floor and return immediately."
If this was indeed related to the Origin, their technological level might exceed even that of Hourai Island. Laojun ordered an immediate withdrawal, but only after ensuring they could return later.
As instructed, Command 2 disembarked from Mini-Mole 2, found a small gap in the metal floor, and installed a tiny marker. It then scrambled back into the Mini-Mole upon hearing the sound of footsteps.
Just before Command 2 and Mini-Mole 2 vanished via the emergency transporter, a figure appeared in the room.
"That was..."
The figure was only on screen for a fraction of a second, but that was enough for Laojun. Mini-Mole 2 returned to Shinkai and was then sent back to Hourai Island via the Warp Gate.
"Good work, Command 2."
While acknowledging the golem, Laojun contemplated the figure he had glimpsed.
"That was... undoubtedly of the same kind as No. 700672..."
No. 700672 was a servant created by the Origin, who had migrated to Ars from Planet Hale aboard the Heavenly Ship. In truth, he was a homunculus—an artificial creature with a synthesized organic body granted pseudo-life. While their knowledge was slightly inferior to that of the Origin, there was a vast gulf between them and the humans of this world. To be blunt, he was considered to be more knowledgeable than even Jin.
"However, I wonder if the slight sense of visual discrepancy was because the model number was different..."
With too little basic information to reach a conclusion, Laojun decided to try a different approach. He would use the marker to send in the Shinobi Squad. He chose them over the Command units because of their specific roles: the Command units were technically gifted, whereas the Shinobi Squad specialized in covert operations.
"But at three thousand meters underground, the built-in emergency transporters are unreliable."
The golems were equipped with short-range transporters for emergencies, but these required a marker at the starting point and only had a range of about fifty meters.
"It is too dangerous unless we can give them enough range to at least return to the surface."
Laojun finally decided to report the situation to Jin and seek his judgment and technical assistance.
"Hmm, I see."
Later that night, after Hanna had fallen asleep, Jin returned to Hourai Island. Elsa remained in Kaina Village, so only Reiko was with him now.
"An underground facility, huh... I wonder if No. 700672 knows anything about it?"
Jin considered asking him later. For now, he focused on Laojun's request.
"Hmm, even if we want to extend the range of something that small..."
Since the golems were only five centimeters tall, they were naturally limited by their size.
"My Lord, could we perhaps use this?"
Laojun showed Jin a fragment of Elradrite. It had been recovered during the drilling process, and even the largest piece was less than four millimeters across. However, it was sufficient for use in the Shinobi Squad. If amplified with Elradrite, the transporter range would increase by twenty times normally, and approximately thirty times at maximum. Using two pieces would make a three-thousand-meter teleportation a simple task.
And so, two units of the Shinobi Squad equipped with Elradrite—Shinobi 1 and 2—were deployed to the underground facility via transporter.