The Barrier’s Secret

"Well, I'd say it's a reverse psychology tactic.

Stationing a large number of guards at the library is like putting up a sign that says, 'SOMETHING IMPORTANT IS HERE.' It would immediately draw attention.

After all, it's unnatural for a library to have as many guards as a Magic Tower or other high-value strategic locations, even if it holds magical books or grimoires.

By keeping security light, they make it seem insignificant—despite it actually being the most critical location.

Putting more guards on the library is basically advertising to any potential spies that there's something important there. It's also rather unnatural for a library to have as many, or close to the number of guards places like their magic tower and other strategic facilities have, even if the library has some magic books or grimoires.

So, by placing fewer guards, they make people focus less on it, despite it being the place with the most important items.

Of course, fewer guards means they're likely relying on high-level automated security instead.

But we were provided with artifacts that far surpass this world's level of magi-technology, so as long as we play our cards right, we should be able to bypass the security."

Xaren wrapped up his explanation just as their meal finished cooking, slicing the meat and skewering a few pieces before handing it to Ilya. He then flipped to the next section of the file.

"Now, the barrier core. Our retrieval target."

The paper he held bore an illustration of a humanoid figure.

"Spirits."

Ilya murmured the word, and Xaren gave a silent nod in response.

The core powering the barrier of Zlego City wasn't an object—but a person. A member of the Spirit race.

"Spirits are beings closely related to 'nature'. The barrier mechanism relies on tapping into the spirit's affinity for the world's natural energies, using them as a conduit to channel large quantities of that energy into sustaining the barrier."

Xaren explained the mechanism, and Ilya studied the illustrations in silence for a few moments before asking him.

"Have you ever seen a spirit before?"

"I've only been out of the newborn zone for three months. Haven't had the chance yet."

It was the truth. Spirits were something he hadn't encountered—at least not in this life.

"From what Floch mentioned in passing when he was teaching me about fire magic, they can switch between 'Material' and 'Spiritual' bodies at will.

In their Spiritual bodies, they can be right next to you, and you wouldn't even notice unless you were perceptive enough to sense their magic or were significantly stronger than they are."

"That makes them the perfect infiltrators, no?"

Ilya asked with a tilt of her head, but Xaren shook his in response.

"Their Spiritual bodies do give them an advantage, yes, but not as much as you might think. As I said, you can still sense their magic power, enough to get a rough idea of where they are—even if you can't see them.

They're also more vulnerable to certain kinds of damage in that form since they lack the protection of a physical body. There are other factors too, but those are beyond what I know."

When Xaren explained this to Ilya, her eyes widened slightly. He was about to ask what had surprised her about his explanation when she spoke up.

"This is the first time you've said there's something you don't know."

"…"

Xaren blinked at her words, realizing with a hint of amusement that his earlier guess was right—she really did see him as some sort of walking encyclopaedia.

"Of course, I don't know everything. There's far too much I don't know."

Xaren never truly believed that for a moment.

For his current age, rank, and circumstances, he might seem knowledgeable, but he knew better than anyone how limited his understanding of the world truly was.

That's why he'd taken advantage of Floch's favour to ask as many questions as he could, hoping to broaden his knowledge.

Compared to his past life, though, he was definitely more knowledgeable now.

For example, back then, he thought High-Rank Demons were the toughest guys around, but now he understood there were Peak Ranks, Demon Lords, and Kings above them.

"But you know a lot. So much that I started to wonder how you got this information."

Ilya continued, her voice thoughtful.

"Like the reason we were told to burn these files or the scare tactic you mentioned earlier. Those aren't things demons at our level would normally know.

If I asked 10 random demons about those two things, I'd bet 8 out of 10 would respond with some variation of 'I don't know.' The other two would probably try to act like they do, but they'd be bluffing."

Xaren chuckled softly at her analogy, tearing a piece off his skewer before replying. 

"It never hurts to have more information. So, I make sure to gather as much as I can, however possible." 

For Xaren, whose goal in this second life of his was 'Survival', information was key.

"Enough about me, let's continue the review."

Xaren tapped the next paper in the stack as he spoke, tearing another bite from his skewer while scanning the contents.

This page detailed the barrier mechanism and the procedure for safely removing the spirit being used as its core.

The spirit was essentially imprisoned within the barrier core, and their prison required magic power to function. It could not absorb ambient energy on its own and relied on regular magic power replenishment to prevent weakening that would allow the spirit to escape.

As for how the demons knew so much about the barrier—its design and even the flaw in the spirit's prison—that was because they were the ones who had originally created it!

Indeed, the barrier around Zlego city was a demon creation. From another world, at that.

It had been designed to capture spirits, but when the military outpost housing the barrier core and materials was attacked shortly after its arrival on Zorix 1I, the technology was leaked.

The barrier materials eventually ended up in the hands of Zlego City's mages, who discovered its functions by studying the blueprints left behind in the fallen outpost.

However, the humans were unable to improve upon it. Though they tried, their attempts were futile.

The magi-technology behind the barrier's construction far surpassed the highest levels of magi-tech on Zorix, after all.

The blueprints they found were simplified versions, made for the demons of this world to easily understand—but the humans weren't aware of this.

Lacking both the knowledge and the materials to make any improvements, the humans could only use the technology as it was.

There were two methods to activate the barrier using the stolen materials. One was simple and easy to use, while the other was an experimental method.

However, given this world's low magi-technological level, the experimental method—which was far more difficult to utilize due to magic power interference from the ground—didn't seem like something they could employ.

As Xaren read on, his mind drifted to memories of the cities he'd participated in attacking in this world, as well as the demon outposts he'd been to.

The technological gap was vast.

This was to be expected, as the demons could draw from the technology of other worlds they had conquered to advance their own.

Their infrastructure was far more advanced, with vehicles like cars, buses, and airships. In contrast, while the more powerful nations on Zorix had airships of lesser sophistication, cars and buses were entirely alien to them.

Moving back to the original subject, Xaren and Ilya's mission was to recover the core of the barrier around Zlego and replace it with something else.

This 'replacement' was among the items stored in the magic pouch they had been given for the mission. Shaped like a giant egg, it had two layers and contained reserves of magic power.

The device held an internal energy reserve within its shell and an external reserve between its first and second layers. Once they swapped it in place of the original barrier core, the external reserve would be drained to temporarily maintain the barrier's functions.

However, once that external energy was completely depleted, the people of Zlego were in for a very flashy surprise.

Naturally, Xaren and Ilya had to be far from the city before that happened—along with the retrieved spirit.

"Alright, so here's the general rundown. 

Our mission is to slip through the cracks in the barrier's weak points, make contact with the sleeper agents, and get close to the library. We'll analyse the security, find the exact location of the barrier core, study the schedule for magic power replenishment for the barrier core prison, and then use the artifacts we've been given to enter.

We'll replicate the barrier core key, retrieve the spirit, and replace it with the 'dummy core' we were given. Then, we need to escape before the magic power runs out and the barrier disengages. 

We're to bring the spirit back alive and likely join the main invasion of the city right after."

Xaren gathered the papers into a neat pile and gave Ilya a quick glance as he asked.

"Is there anything you don't understand?" 

She shook her head, her attention more on her food, and Xaren gave a quiet nod before tossing the bundle into the fire.

With that done, he turned his full focus to his meal, finishing it quickly.

Once they were done cleaning up after eating, Xaren extended a hand toward one of the rolled-up bag bundles he had set aside earlier. The desired item lifted off the ground and flew into his hands.

As he caught it and began unwrapping it, Ilya, who had been observing, posed a question.

"You keep using your skill for small things like that. Is this your way of training it?"

She was referring to Xaren's use of gravity magic to pull the item into his hand, despite it being close enough to grab manually.

"Small things, you say?

You're not wrong in assuming it's my way of training, but none of the actions I've taken with it can be considered small."

Xaren tossed the folded sleeping bags over the fire, then generated an Attraction force to pull them back into his hands.

"In this seemingly small action, I have to regulate the amount of magic power I use, as well as the speed and force, otherwise, the bag could end up flying at me at the speed of sound."

Well, maybe not quite sound speed, but objects he pulled could easily travel at over half that. Depending on the item, the result could be anything from completely ordinary to outright disastrous.

"How fast is sound?" Ilya asked with a tilt of her head.

In response, Xaren picked up one of the few papers he hadn't burned—the map to Zlego—and spoke.

"A sound wave could travel from one end of the ravine to the other in three seconds."

"…That's fast."

"It is. Now imagine what would happen if an object came flying at me at that speed."

"…"

Ilya remained silent as her mind conjured the gruesome image, then gave a quiet nod of understanding.

Xaren handed her an unfolded sleeping bag, and she arranged it on the floor near the fire. He then adjusted their campfire's flames to a lower burn and set up his own sleeping bag.

After sprinkling some monster-repellent powder around their campsite, they turned in for the night.