Ultrasonic vibration? Leon asked internally.

—Yup.

The concept was far too foreign to Leon, so El Cid took a moment to choose his words before explaining. Adela’s earlier explanation had already been simplified as much as she could manage, but to someone without the slightest foundation in such matters, it might as well have been mysticism or nonsense.

The microscopic world was a metaphysical realm one could approach through will and the metaphysical counterpart to the physical world’s deepest scientific truths.

—As that gnome said, all forms of energy originate from vibration. Heat is caused by the vibration of microscopic particles, and sound is produced when air layers oscillate and transmit waves.

I remember hearing that sound is vibration.

—Right. And there’s more. Every material thing in existence vibrates at its own natural rhythm, even without external force. Each substance follows its own distinct, consistent pattern.

It was the concept of a natural frequency. Adela had reached that understanding through centuries of martial and experiential refinement, not through scholarly study. She couldn’t describe it in theoretical terms or teach it systematically—she simply knew it.

That, too, came from her race’s extraordinary sensitivity. There was no way to explain such experience-based perception to other species that lacked it.

—What you just saw was an application of that natural frequency.

As El Cid had said, everything in existence had its own innate frequency. When a matching frequency was applied to it, the amplitude of vibration increased dramatically.

In sound, this was called resonance. In motion, it was vibrational resonance. The examples were countless, such as bridges collapsing from mere wind or wine glasses shattering at a high note of an opera singer.

But Cardinal Adela’s technique... that was far beyond that.

She had only touched the wall. She hadn’t struck it, hadn’t used any penetrating attack, hadn’t even forced energy inward. She had merely caused the Aura around her hand to vibrate, and yet the famously solid wall of Portroi had crumbled into dust.

To El-Cid, however, it seemed like it wasn’t anything significant.

—I told you. It’s just an application. Works even better on solids than on liquids, and better on liquids than gases. The principle isn’t all that special. What’s special is having that much control over one’s own Aura to be able to manipulate it that way.

Leon, Karen, and Elahan had all reached the rank of Aura Master themselves, yet none of them could hope to manipulate Aura with such finesse. That was the true gulf of mastery.

The level of fundamental skill refined over centuries—polished and built up layer by layer—was nothing short of perfect. No amount of talent or genius could bridge that overnight.

While the three were still in awe, Adela shouted, “Why are you all standing there like stunned chickens? Get it together and follow me!”

Elahan, Karen, and Leon hurried after her, climbing through the gaping hole in the wall. Days of planning their infiltration into Portroi had ended in mere minutes.

“Oh. Maybe we should at least patch this up a bit.”

Manipulating earth wasn’t a dwarven specialty alone. With a single wave of Adela’s hand, the soil around them lifted and filled the two-meter-wide gap in the wall perfectly.

It wouldn’t fool a careful inspection, but out here on the outer perimeter, patrols were sparse. Unless an inspector came by, they wouldn’t be discovered.

And so, the four successfully infiltrated Portroi. After several minutes of walking beyond the outskirts, they reached an area near the main road. From the shadows of a narrow alley, they discussed their next move.

“The city’s not as heavily guarded as I expected. As long as we blend in with the crowd, we shouldn’t have to worry about checkpoints,” Leon said.

“Hm. That might be true for you, Hero, but our little sweetheart and the young lady here kind of stand out. Any man with working eyes would have a hard time not staring.”

“You’re not wrong...” Leon admitted.

Even at night, the two women shone. Elahan’s silver hair and golden eyes alone could draw a crowd, and Karen was beautiful enough to turn heads anywhere she went. Soldiers would have every excuse to “inspect” them just to strike up a conversation.

“Tch, guess we’ve got no other option. Looks like I’ll have to do some extra work again. Like always.”

At that, Adela’s expression soured—not annoyed, not troubled, just... deeply reluctant, like a child being forced to eat vegetables she hated. The others watched her expectantly, then widened their eyes in surprise at what she said next.

***

Despite the unrest spreading throughout the Empire, the vast and prosperous domain of Portroi, the Gateway City, remained untouched. The rebel forces were far away, and being so close to the Imperial Capital of Calelum, it made it a difficult target.

Even under wartime restrictions, the people of Portroi lived as they always had, working, laughing, and walking the streets without worry.

“Oho, a young married couple!”

A carpenter repairing a sign from his ladder called out cheerfully to a pair walking by. For older folks, there was no sight more pleasant—or more fun to tease—than newlyweds.

An elderly man nearby looked up and carefully said, “Don’t recall seeing your faces before. You from another territory?”

The young man with brown hair nodded lightly and replied, “Yes, sir. Things got pretty rough back home. Thought we’d try our luck in Portroi. The land’s wide enough. There’s bound to be work somewhere.”

“Haha, smart thinking. Not quite as safe as the Capital, but this place is still one of the Empire’s most secure domains. You’re a thoughtful one, for someone so young. Isn’t that right, miss?”

A beautiful woman with silver hair and golden eyes—colors so rare they seemed almost unreal—smiled gently.

“Yes! I’m lucky to have such a dependable husband!”

“I’ve told you many times, Ella, it’s me who’s undeserving,” the young man said to his wife with loving eyes.

“Oh, stop it, you.”

The elderly man chuckled warmly at their shameless display, then pointed toward the little girl standing between them.

“Still, it’s good to see young folk like you. These days, everyone’s so scared they won’t even have children—but here you are, with one already this big! Makes an old man’s worries feel pointless.”

The child, a girl with light brown hair tied in a single braid, blinked her large, green eyes.

“Grandpa, am I already big?” she asked.

“Hmm? Well, if you can walk and run on your own, I’d say you’re all grown up. Don’t you think so?”

“Aw, but I don’t wanna be grown yet... I still have to get taller! And wear pretty clothes like Mama!”

Realizing his slip, the old man laughed heartily and grabbed a small toy from his stall.

“Ah, I was wrong then! You’ll grow much taller. Play with this, and you’ll grow up even faster.”

“Really?! Yay!”

Her face brightened instantly, blooming into a radiant smile so pure that everyone nearby stopped in their tracks to look. Give her another ten, maybe twenty years, and she’d become a woman impossible to look away from. That much was certain.

As the family of three disappeared down the street, people smiled to themselves and went back to their business. Then, the moment they stepped into a quiet alley, the little girl roughly shook the stuffed toy she’d been holding.

“What is this ragged thing supposed to be? A bear? A rabbit?” Adela grumbled.

And yet, she didn’t throw it away. Perhaps because it was a gift given out of pure goodwill. Leon smiled faintly, half amused, half sympathetic.

Who would’ve thought Cardinal Adela would be the one to suggest this plan?

This little act had been her idea: Leon and Elahan would pose as a young married couple, and Adela as their daughter.

Two adults traveling alone might draw suspicion, but a couple with a child? People dropped their guard almost instantly. The carpenter and the old man who had spoken first—both had done so precisely because Adela’s presence disarmed them.

Karen’s voice whispered faintly from Leon’s shadow.

“I’ll admit, I was impressed, Mr. Hero. I couldn’t keep a straight face when the Cardinal smiled like that.”

With her stealth abilities, she’d moved freely since they’d crossed the magical barrier. She had considered splitting off to gather information, but there was still a Grand Mage in this territory. There was a chance that they might very well be able to pierce even the concealment of Pitch-Black Dance.

“Barely managed myself. Elahan pinched her own thigh so hard I’m surprised she doesn’t have a bruise.”

“Still, the Cardinal’s incredible. If I were that old man, I’d have fallen for it too.”

Even a top-class assassin couldn’t detect a hint of falsehood in her act. It was only knowing who Adela truly was that made it so hard to endure; her behavior had been that of a perfect child.

Perhaps sensing their whispers, Adela scowled, clearly displeased.

“So, Hero. What’s the plan for this domain?”

“What do you mean?” Leon asked.

“If your destination’s Calelum, there’s no point staying here long. Linger too much, and the Grand Mage will catch on. If we’re going to the Capital, we should cross the wall tonight.”

However, Leon felt a strange resistance to that idea. He couldn’t quite explain it, but something deep inside warned him they shouldn’t move yet. That crossing now would be a grave mistake.

He replied, “Let’s stay a few more days. I’ve got a bad feeling about heading to Calelum right now.”

“A feeling, huh? Is it sort of like the Saintess’ revelations?”

Adela frowned for a moment but soon nodded, accepting the Hero’s judgment. Then her eyes narrowed toward a distant watchtower.

“The formation of that barrier magic... its mana flow feels familiar. Don’t tell me that old bastard’s still alive?” Adela muttered.

“Is it someone you know?” Leon asked.

“Know him? I crushed his left leg myself.”

Despite appearances, Adela ranked among the Church’s top three in seniority and skill. During the Clyde Empire’s conquest campaigns, she’d been sent multiple times to clean up the chaos left behind.

Grania, the former Archmage of the Tower. She had faced the Grand Mage as an enemy back then.

“I heard his disciple reached the seventh tier and that he retired to some borderland for research. Didn’t think he’d crawl back here.”

Adela looked genuinely puzzled, but Leon and the others exchanged tense looks, thinking of Dayton. If he hadn’t come of his own free will, then perhaps...

Then, it happened in an instant. Adela’s eyes widened, and she whipped her head toward the watchtower, clenching her fist.

“Ah.”

Only El Cid understood why.

—We’ve been discovered.

What?

—Seems the barrier surrounding the walls was coupled with a periodic scanning spell. A wide pulse of mana just swept across the area.

Wait, just that was enough to expose us?

They hadn’t used any stealth skills like Karen, but they had completely suppressed their Aura, freezing even its flow. And yet, one brief wave of mana had been enough to reveal them? To a non-magician, it was an impossible notion.

—To a mage, their domain is like their own body. They can’t control it perfectly like an Aura Master, but detecting foreign presence within it is easy.

Before El Cid even finished speaking, all four of them felt an overwhelming presence approaching. A vortex of power, not quite the same as an Aura Master’s, was coming, fast.

As if caught in the eye of a storm, the very air around them stilled. If Aura Masters carved their will upon the world through strength, a Grand Mage ruled it through wisdom and sorcery.

“Been a long time since I’ve seen that face,” a man said, hovering above them.

His entire body was wrapped in robes, only an aged, wrinkled face visible as he stared directly down at Adela. There wasn’t the slightest hint of warmth in his gaze. His eyes brimmed with hostility as he spoke.

The former Archmage of the Clyde Empire added, “I don’t recall sending you an invitation. What’s a hog from the Holy Church doing in my territory?”

In response, a sharp crack rang out from Adela’s clenched teeth.

“Hog...?”