Peru’s Juggernaut, the Golden Ark, moved serenely across the sandy sea of the Heat Nation’s land.

Even in strong winds, the steel behemoth didn’t sway. It crushed boulders underfoot with ease and climbed steep hills as if they were gentle slopes. The name Golden Ark was perfectly fitting. Unlike the ocean, where waves could hinder progress, the land offered no such obstacles to impede the Ark’s advance.

We settled into the cabins below the deck and enjoyed the most comfortable journey we’d had in a long time. Tir sat in a chair, evaluating the ride of the Golden Ark.

“Smooth and quiet. It’s hard to tell whether I’m riding in a vehicle or seated in a stately palace. This is the most impressive marvel I’ve encountered recently.”

Though her expression didn’t show it, Peru seemed pleased as she responded.

“…It’s substitution movement.”

“Substitution movement? Hmm, what is that?”

Realizing that Peru wasn’t skilled at explaining, Tir naturally turned to me. What am I, some kind of vending machine for answers? I don’t know everything either.

Well, in this case, I did know—since I’d read Peru’s thoughts.

“It’s an alchemical technique that’s considered theoretically the most advanced form of movement. Tir, usually when you want to move quickly, obstacles get in your way, right? Like headwinds or protruding rocks.”

“Or sunlight.”

No, sunlight wouldn’t really count. Anyway...

“If you could break down those obstacles with alchemy the moment you encounter them, nothing would stand in your way. You could move forward without any hindrance.”

“Hmm, I see.”

“Exactly. Furthermore, if you restore those obstacles after passing through, you could even gain a push from them as they reform. You’d also recover some of the magic spent breaking them down.”

This is substitution movement, a technique devised by a genius in alchemical theory.

Tir, pondering the concept, clapped her hands once she understood.

“So, theoretically, you could move across the ground as if sailing with a tailwind!”

“In theory, yes. You could even stroll through the earth itself. Though, again, that’s just ‘in theory.’”

As in most things, “theoretically possible” often means “practically impossible.” If it were so simple, it wouldn’t remain a legend.

“In practice, it takes time to break down obstacles with alchemy. If you don’t do it properly, leftover magical residue can become a new obstacle. And no matter how efficiently you reconstruct things, you can’t recover 100% of the magic you use. It’s close to impossible.”

“Close to impossible means not entirely impossible, doesn’t it?”

“There are rumors about scavengers who use substitution movement underground. They call themselves ‘moles’ instead of scavengers. But they say it’s so slow that it’s only useful for ambushing sleeping targets. If it’s that slow for humans, how could anyone turn it into a practical device? It’s absolutely impossible.”

When I stated this firmly, Tir tilted her head and asked again.

“But it’s been done, hasn’t it?”

“Huh?”

She was right. How had they done it?

Even with a unique magic like Peru’s, which has the ability to dismantle matter, it’s a rare and extremely limited power. How could that ability be applied to a massive Juggernaut like this?

I had no answer. Are we even the same species? Even as the king of humans, I couldn’t fathom it. What kind of monster is she?

“This, too, must be the greatness of Golden Mirror,” I said, deflecting.

“…Mm.”

Hearing my comment, Peru let out a small, satisfied breath. I wasn’t even complimenting her specifically—why was she so smug? Have you merged with Golden Mirror? Do you take any praise of him as praise for yourself?

“This is a total cheat!”

Ah, here we go again. Someone had to take it personally. Hilde stomped her feet and voiced her complaints.

“They don’t even understand the structure of the Juggernaut! They don’t know how it works! They’re just using it because Golden Mirror gave it to them! Unlike the Military Nation’s Cataphracts, the Juggernauts don’t have the blood, sweat, and tears of hard work!”

“…This, too, is the greatness of Golden Mirror.”

Oh, you liked that line, didn’t you? You’re already reusing it.

Hilde, visibly annoyed, grumbled under her breath.

“Ugh, how impressive.”

She stomped the floor again, mixing a bit of martial energy into her step. The kick was meant to be destructive, but the Juggernaut didn’t even dent.

This, too, must be the greatness of Golden Mirror.

“Tch! This won’t do. I’ll have to show off the Military Nation’s greatness myself!”

“And what greatness would that be? Surely not a demonstration of your standard martial techniques? Just so you know, that’s not something to brag about. The more you show it off, the more it lowers your national dignity.”

“Hmph, do you think I’m some old general? Of course not! Father, keep your mouth shut!”

Huffing, Hilde suddenly pointed upward as if remembering something.

“Oh, right. Peru, I saw Azi chasing your horse on the deck earlier.”

“…Ah.”

Peru’s horse, Aurea, had been grazing peacefully in a small plot of grass on the deck. While Aurea had likely been enjoying the comfort of the moving ground, Azi was now relentlessly chasing her around, barking and trying to assert dominance. Poor Aurea whinnied mournfully, and Peru had to keep going up to separate them. Azi, for all his mischief, did listen to humans.

“…I’ll be back.”

Having heard Hilde’s report, Peru immediately opened the door and went to the deck. Hilde smirked mischievously and followed her quietly, her footsteps hushed.

A short while later.

‘Peru’ returned, walking with hesitant steps and an awkward expression. Glancing around, ‘Peru’ asked cautiously.

“…Liar. Where is it?”

Tir raised an eyebrow at the unexpected remark and answered curiously.

“Liar? Who are you referring to?”

“…Aurea. Grazing.”

“If you mean Hilde, didn’t she follow you just now? Didn’t you see her?”

“…No.”

“She must be up to some mischief. Hilde is known for her antics.”

“Why are you looking at me like that?” I protested. “I had no part in shaping Hilde’s personality. I’m not responsible for her pranks.”

As I was offering my feeble excuses, the door to the deck opened again. Everyone turned their gaze to the entrance, where Peru entered, her face set in a disgruntled expression.

“…Liar. Where.”

Peru and ‘Peru’ came face to face.

Peru’s face went pale. Likewise, ‘Peru’ froze, trembling slightly as if in fear. The two stared at each other warily, like cats with their hackles raised.

“…What’s this?”

“…Who are you?”

Two identical individuals stood in the room—a bizarre situation, but one we had seen before. Tir, having already experienced Hilde’s transformation magic, quickly pieced it together.

“Ah, it’s another prank. That transformation magic again, is it?”

“…Transformation? Magic?”

“…You turned into me?”

Now understanding the situation, Peru began to relax slightly and scrutinized her duplicate from head to toe. The face, the clothes, even the height and physique—everything matched perfectly. It was as if the other had been photocopied.

The level of replication was unnervingly close to perfection. While impressive, Peru’s expression showed more discomfort than admiration.

‘…Impossible. A chieftain can’t create a homunculus. I know that. But….’

A homunculus?

Haha. What nonsense. A homunculus is even more impossible than substitution movement. Hilde’s transformation magic, while advanced, cannot replicate someone’s mind or spirit.

Creating an exact duplicate of a human? That’s the stuff of legends, not reality. Why is Peru seriously considering such a thing?

Wait—don’t tell me. Could this, too, be the greatness of Golden Mirror?

Ahem. Now’s not the time for idle thoughts. Hilde’s prank was clearly upsetting Peru. If it were me, I’d use my mind-reading ability to carefully navigate the situation. But Hilde? Not a chance.

“Alright, Hilde. Enough. Reveal yourself. It’s not okay to play tricks like this on someone you’re not close to.”

‘Peru’ widened her eyes in feigned surprise and asked, “…You know who I am?”

“Don’t act like you don’t. That’s obviously Hilde.”

“…How did you know?”

Determined to keep up the pretense until convinced otherwise, ‘Peru’ pressed further. I sighed, ready to offer a logical explanation.

“I’ll tell you why. First, Hilde left after Peru. Since neither of you crossed paths, it’s simple deduction that Hilde must be the one between Peru and this room.”

“…But she could have hidden somewhere.”

“Second, Hilde’s intent was to surprise Peru, right? It’s more shocking to enter and find another version of yourself already present than to have a duplicate walk in afterward.”

“…Circumstantial evidence.”

“I don’t need absolute proof. A plausible explanation is enough. Besides, you’re not even trying to draw this out anymore.”

‘Peru’s’ expression began to change. Her neutral face shifted to one of annoyance, puffing her cheeks in mock frustration. Eventually, her features reverted to Hilde’s as she stomped her foot in faux indignation.

“Ugh! This is why I told you to stay quiet, Father!”

“I heard you. I just didn’t listen.”

“You’re the worst! Stealing one of my few joys!”

What a lie. While transformation may be one of Hilde’s favorite amusements, her real goal isn’t to stay hidden but to be found. She transforms in the hope that someone will notice.

So why complain when it goes exactly as she wants? Just admit you’re enjoying it. Or maybe… you already are.

“Are you ready to admit it now? I can easily see through Hilde’s disguises. To someone who understands the psyche, a superficial transformation is as clear as day.”

Feeling triumphant, I puffed up slightly. Tir clapped politely, acknowledging my insight.

“As expected of you, Huey. I wouldn’t have noticed, having known Peru only briefly, but you saw through it instantly.”

“Oh? Tirkanjaka, are you saying that if you knew someone better, you’d recognize the difference?”

Apparently unable to let this slide, Hilde pounced on the statement. Tir calmly deflected her aggression with a serene smile.

“Of course. How could I not know someone I’ve observed for so long?”

“You didn’t notice when I transformed into Father last time, but now you’re so confident?”

“I had my suspicions back then. However, not knowing your power, I hesitated to jump to conclusions. Now that I understand your abilities, it’s crystal clear.”

“Oh, really? But what if I’ve gotten to know you better, too?”

Zap. Sparks flew between the two women as Hilde raised her chin defiantly.

“Let’s settle this! Try to see through my next transformation!”

“Go ahead and perform your little tricks. At least the journey won’t be boring.”

As the two locked horns, Peru watched them with a look of sheer disbelief.

‘…What are they doing in someone else’s house?’