Jin’s prototype proved to be a success as well.
He was seeing an image identical to what he would get by placing a magic eye twenty meters ahead. Better yet, it didn’t matter if there were walls or solid rock in between.
“This is an unexpected benefit.”
When he thought about it, the result was only natural, as the device utilized ether waves rather than light waves.
“This is X-ray Vision in the truest sense.”
Reiko possessed a function also called “X-ray Vision,” but hers relied on things like infrared, which came with the caveat of only working “to a certain extent.” She could not obtain images as vivid as these. Furthermore, with this new method, it would likely be possible to see through objects from a great distance.
“We’ve created something incredible.”
Jin paused to reflect.
“It’s possible that Helente could do the same thing to us.”
He began to consider countermeasures for such a scenario.
“I suppose a barrier is the only answer.”
Jin decided that while they might not need to shroud the entirety of Hourai Island, they should at least have barriers that could individually protect the laboratory, the house, Laojun, and other critical points.
『You are referring to a magic barrier, then,』 Laojun remarked.
“That’s right. It would be ideal if we could also deploy a solid barrier as a separate layer.”
『Understood. I will make the necessary arrangements immediately.』
He had taken a slight detour, but Jin felt a sense of relief now that one of his concerns had been addressed.
“Let’s try combining this with Elsa’s prototype.”
“Mm.”
With a bit of additional processing, the integration was complete.
“Alright, wake up.”
He pointed the device toward Kunlun Island, which sat approximately 300 kilometers away.
“Hmm, just a little more.”
Adjusting the direction was proving to be unexpectedly difficult. Even a shift of 0.1 degrees resulted in a massive error over a distance of 300 kilometers.
“Jin-nii, how much of an offset would that be exactly?”
“Eh? You can figure that out with trigonometry, right?”
“Let me see...”
Elsa seemed to have the theoretical knowledge but had never actually applied it.
“It’s tan = b/a.”
“Ah, then if ‘a’ is 300 kilometers and ‘is 0.1 degrees, the error we’re looking for is ‘b,’ right?”
“Exactly.”
People really are divided into those who use trigonometry and those who don’t, Jin thought to himself, though he kept the observation private.
“In that case... b = 300 × tan(0.1 degrees).”
“That’s the one.”
Jin could have asked Laojun to calculate it, but he was currently relying on a table of trigonometric functions found in the appendix of a book brought by the Magus, Shuuki Tsetse.
『It is approximately 523 meters,』 Laojun calculated as soon as Jin provided the formula.
“An error of over 500 meters from just 0.1 degrees...” Elsa said, her expression turning somber. “I see now why you want to reduce the margin of error to zero, Jin-nii.”
“Right?”
Jin realized that if they extended this to astronomical distances, it might be impossible for a human to operate it manually.
“We’ll either need a dedicated golem for the task or make the system semi-automatic.”
“Jin-nii, look. For now, I can see what looks like Kunlun Island.”
“Oh, impressive.”
While Jin had been lost in thought, Elsa had finished the adjustments. The image vibrated slightly, but it was more than clear enough for confirmation.
“Hmm. If we build this properly, it’ll be perfectly practical.”
Short to medium-range use didn’t seem to pose any issues.
“And it has X-ray Vision to boot...”
Jin decided to name the device the “Peeper.” He had briefly considered calling it “Peeping Tom,” but he exercised a bit of self-restraint. With a device like this, one could peer into a room through the walls.
“We’ll have to make sure we don’t use this indiscriminately.”
“Mm, I agree.”
Aware of the moral implications, Jin and Elsa both vowed to refrain from using the device lightly.
The real challenge would be the version for space observation—the long-range to ultra-long-range models.
“For anything beyond long-range, we’ll need a much larger and more rigid structure.”
Since the underlying principle was the same, the construction itself wouldn't be a problem.
“Laojun, please look into the necessary strength, size, and reachable distance.”
『Understood. Please leave it to me.』
Leaving the heavy lifting of the design to Laojun, Jin and Elsa took a break.
“Father, what would you like to drink?” Reiko asked.
“Let’s see... citran juice.”
“Understood. And for Elsa-sama?”
“The same for me, please.”
Reiko brought the two of them glasses of chilled citran juice.
“Still, we managed to make it work.”
“Yeah, we did.”
“As expected of you, Father!”
Elsa and Jin lightly clinked their glasses in a toast, while Reiko added her own praise.
“All that’s left is the energy transfer, but... honestly, the priority on that is low.”
Jin couldn't deny that a significant part of his motivation was simply not wanting to be outperformed by Helente.
“More importantly, we can apply the Peeper technology to create some powerful weapons.”
“...That’s true.”
“I don’t really intend to use them, but we should build some just in case.”
They could simply substitute a Light Ball with an attack magic formula. It would be effective at extreme ranges where normal magic couldn't reach, or against targets hidden behind cover.
“It would be great if we could select the specific magic from our end.”
“If that's the case, we should include Healing as well.”
“Yes, definitely.”
As Elsa suggested, the ability to use Healing magic at a distance would be incredibly useful.
“Since it covers everything from combat to Healing, let’s add this device to every unit in the Hourai Island forces.”
That meant Reiko, Laozi, Soleil, Luna, the Five-Colored Golem Maids, the Land, Sea, and Air Forces, the Smiths, the Marine Force, the Space Force... and even larger versions for aircraft and ships.
“It’ll be a massive undertaking, but I’m counting on you.”
The Smiths were about to be very busy.
Thus, the military potential of Hourai Island was bolstered even further.