Regret is so named because it is felt after the fact.
"I see... So you can make it, Jin. Good grief. To think the person I was looking for was right here all along."
Reinhard slumped his head in dejection. It was only to be expected.
Reinhard himself could easily create a magic tool that simply discharged mana. However, doing so without regulation would lead to a condition known as magic depletion.
It was perhaps easiest to compare it to a magical form of diabetes.
If there is more mana—sugar, in this analogy—than necessary, it harms the body. If it is depleted, that causes its own set of problems.
It was no wonder Reinhard had assumed that no one could create a magic tool capable of stopping at exactly the right point.
Furthermore, even though he had finally come to know Jin’s character recently, one wouldn't normally reveal the physical secrets of a viscount's daughter like Elsa to a man of unknown lineage. Even if they were relatives, she was a lady of another house. In the eyes of the world, simply being known to have a chronic illness could ruin her marriage prospects.
"If Elsa were my own sister instead of my cousin, I would have consulted you long ago," Reinhard said with a self-deprecating smile. Now, it was too late.
Just then, there was another knock at the door. Anne opened it.
"I figured you would be here, Reinhard."
The visitor was Fritz.
"I'm sure you've heard, but Elsa has disappeared. Her wet nurse, Mine, is with her. I will be the one to track them down. Therefore, Reinhard, you are free to go."
"Eh?"
Reinhard couldn't quite grasp the meaning of the words. It was a rare lapse for someone as quick-witted as him.
"In short, you no longer need to play babysitter for Elsa. You've done your part."
Having said his piece, Fritz turned on his heel and left without waiting for a response. From start to finish, he didn't even look at Jin.
"..."
"..."
Silence stretched between the two. Then, as if on cue, they both let out a heavy sigh.
"Well, that’s that. Jin, we’ll be leaving here tomorrow. Do you still want to visit my country?" Reinhard asked with a lonely smile.
Jin answered immediately. "Yeah, of course. So, we're departing tomorrow morning? What's the plan for today?"
Hearing that, Reinhard’s expression brightened.
"I see! Thank you, Jin. I was worried you might have come to dislike my country after all this trouble. I'll be out all morning handling the departure procedures. I plan to be back by the afternoon."
"Got it. I'll find some way to kill time until evening."
Jin acknowledged the plan, and the two went their separate ways for the time being.
＊ ＊ ＊
After a quick breakfast at the hotel, Jin warped back to Hourai Island.
He had a specific idea in mind.
He wanted to build a magic tool to find Elsa’s whereabouts. Assuming Elsa was still wearing the dagger and brooch Jin had made, those two items should be imprinted with his own magic pattern.
He excluded the Protect Ring, as it would have likely synchronized with its owner's mana by now.
Essentially, he intended to create a high-performance magic detector.
"My Lord, are you not continuing with the armor today?" Laozi asked.
Jin nodded. "Yeah. I thought of something else. Help me prepare the materials."
"Understood."
What Jin intended to make was an advanced version of a magic detector—a magi-device that could sense an individual's mana and pinpoint their location.
In truth, after the Predecessor passed away, the automata that preceded Reiko had spent about fifty years developing such a device to search for a successor.
However, over the course of a thousand years, that device had been destroyed beyond repair after Jin was found. Furthermore, the automata's knowledge had been partially lost, meaning the technology couldn't be reproduced. There wasn't even a trace left in the records or memories that such a magic tool had ever existed.
Thus, Jin had to build it from scratch.
The basis was the sensor installed in Reiko. It could tune into a specific mana signature and determine its strength and direction, though its precision was limited.
Jin planned to install three large-scale versions of this on Hourai Island.
If the direction was known, drawing straight lines from two distant points would show the location at the intersection. Since the three points would be fixed, Jin figured that having three sensors—to account for any scenario where the target fell directly on the line between two sensors—would provide high accuracy.
Much like radio waves, mana synchronization relied on the principles of resonance and sympathetic vibration. Instead of coils, he used magi-crystals engraved with magi-formulas. Jin carefully inscribed the patterns.
Beside him, Reiko manufactured the housings and support legs for the sensors according to Jin's instructions.
Watching this, the island's central intelligence, Laozi, found himself wishing he had limbs so he could be of more use to Jin.
However, Jin soon ran into a problem: how to quantify the direction in which mana was detected. In his original world, there were compasses and the position of the North Star.
"Right... I'm going to need a compass for ship and aircraft navigation eventually anyway."
Jin temporarily stopped assembling the sensors to make a magnetic compass.
As an experiment, he decided to magnetize a steel needle, stick it through a piece of paper, and float it in a basin of water. He had the needle, the paper, and the basin, but magnetization was the hurdle.
Ultimately, he used Forming to turn copper into wire and coated the surface with the sap of a tree similar to lacquer for insulation.
By connecting this crude enameled wire to a battery made of alternating thin plates of copper and zinc separated by cloth soaked in citran juice, he created an electromagnet.
He used the steel needle as the iron core to magnetize it, and finally, the magnetic needle was complete.
When he stuck it into a scrap of paper and floated it in the water, the simple compass pointed correctly to the north and south. This proved that this planet also possessed geomagnetism.
Jin then moved on to making a proper compass. The needle was steel, the bearing was a small crystal, and the case was light silver. He divided the dial into 360 degrees and marked the four cardinal directions, the four intercardinal directions, and the eight points in between, for a total of sixteen compass points.
If he wanted more precision, he would need to use landmarks like the North Star, but for now, this was sufficient.
The three sensors incorporating the dials were completed in about three hours. Each had its own independent golem brain and could exchange information via manacam.
He installed them atop the laboratory in the south of Hourai Island, at Tatsumi Bay to the southeast, and on the summit of a small hill in the orchard to the southwest.
"Alright, they're currently calibrated to my mana. Report the directions detected by each."
Laozi was in charge of management. The information was sent to Laozi, who processed it and reported back to Jin.
"My Lord, the strongest reactions are 179 for sensor A, 347 for sensor B, and 61 for sensor C."
A was the laboratory, B was Tatsumi Bay, and C was the orchard. Magnetic north was 0, and the values were quantified clockwise through 360 degrees.
"Yeah, that matches my current position in front of the laboratory perfectly. It looks like this will work. Can you detect the other golems too?"
The golems Jin made all shared the same magic pattern as him. The only difference was the intensity. Therefore, they could be found with the same detector, but...
"There are too many golems on the island to pinpoint individuals," Laozi reported.
If they were right in front of him, there were various ways to identify them, but it seemed impossible with just magic patterns alone from a distance.
"Ah, right. Then what about the flying squadron?"
There were fewer golems flying around for map-making.
"Yes, it is possible to pinpoint those. Their positions are..."
Jin cut him off. "Ah, I don't need a detailed report right now. Instead of numbers, make it so you can report locations by indicating points on the map we've completed."
He instructed Laozi accordingly. It would be difficult to visualize the situation if he was given numerical bearings every time.
"Understood."
With this, Hourai Island was now capable of tracking Jin and his creations.
If he wanted to, he should also be able to find Elsa—or more accurately, the magic tools Elsa carried.
"My Lord, I have a request."
Sensing that a milestone had been reached, Laozi voiced the wish that had occurred to him earlier.
"Could you please create an external humanoid terminal for me?"
In other words, a golem or automata that Laozi could operate remotely.
"If I had one, I could be of even more help to My Lord."
Jin fell into thought. He had intended for Reiko and Laozi to monitor each other to prevent any potential issues, and he worried that providing Laozi with such a terminal might diminish Reiko's current role.
"It does not need to be as powerful as Reiko-san; something around Anne's level would be sufficient," Laozi added, sensing Jin's hesitation.
Jin decided that would be acceptable and gave his permission. "Alright. Do you have any preference for the appearance?"
"Yes. In keeping with the name Laozi, I would like the appearance of an old man."
Indeed, there were currently no golems with the appearance of an elderly man on Hourai Island.
"Got it. Leave it to me."
Jin immediately set about making Laozi's Dedicated Automaton.
The basic structure was the same as Anne's. The primary differences were that it was a male model and that it didn't have a control core equivalent to a brain. Instead, he installed a mana-telecam and a remote magi-device, leaving the control entirely to Laozi.
Consequently, its maximum output was limited to twenty percent of Reiko's.
For the appearance, since it was Laozi, Jin momentarily considered a sage-like design, but he eventually settled on a butler style. It ended up looking like a blend of Elsa's butler, Adberg, and Reinhard's butler, Claude.
Jin didn't tell anyone, but a sage style would have carried too much dignity, and he was afraid he would feel intimidated by his own creation.
＊ ＊ ＊
"One of the targets is acting alone."
"Good. Secure them."
"Understood."
＊ ＊ ＊
Late in the afternoon, Jin returned to Ikasanat from Hourai Island.
Since there was still time before nightfall, he walked through the city searching for shops that sold weapons or armor, hoping to find some equipment for himself. However, he didn't find much. After all, the full-body armor worn by ritters was typically custom-made.
"I'll try consulting Reinhard later," Jin decided.
Giving up for the day, he headed back to the hotel.