518 The Fairy Mother and Daughter, and a Discovery** 

After calling the King of the Iron Nation Gandiris to personally request a steel purchase, he readily agreed—but in return, he asked for a small favor. Is the Iron King consulting me? What could it be…? 

"Well, I’ll find out when I get there." 

"Did you settle things?" 

"Yeah. He said he’ll be waiting at the palace." 

I answered Leen and immediately opened a [Gate]. 

As if she’d been waiting for this moment, Kuhn dove through the [Gate] first. No need to rush that much. 

"Goodness… So restless. I wonder who she takes after?" 

"Hey now, I know you wanna say it’s me, but you were the same way back when we were searching Babylon’s ‘Library’." 

"I was much calmer than this." 

Oh, come on. Even Pola at my feet was tilting her head like, "Really?" 

"Well, she’s your daughter. It’s only natural she’d take after you." 

"I suppose so." 

The two of us exchanged glances and laughed. Then, from beyond the [Gate], Kuhn’s deadpan face poked out, her head alone visible. 

"As heartwarming as this is, shouldn’t we hurry? Keeping His Majesty the King of Gandiris waiting would be rude, don’t you think?" 

"O-oh, right. Got it." 

"Y-yes, let’s go." 

Feeling oddly embarrassed, we hastily stepped through the [Gate]. 

◇ ◇ ◇ 

"Ah, Otou-sama, let’s buy that high mithril too!" 

"Sure, sure, this one, right?" 

Following Kuhn’s instructions, I tossed the gleaming lump of high mithril into [Storage]. 

After greeting His Majesty the King of Gandiris, we were immediately guided to a massive warehouse on the city outskirts, which served as a storage site for steel and other resources. 

Piles of various ores and alloys were stacked like mountains, with refined steel products neatly arranged among them. 

This is an insane amount… As expected of the Iron Nation. 

Gandiris was a mountainous country surrounded by numerous mines. Thanks to its abundant underground resources and advanced smelting technology, most nations on the western continent purchased steel from here. 

Of course, this had led to multiple invasion attempts in the past, but the nation’s rugged terrain and sturdy golems had repelled them all. 

With every kind of mineral available, many dwarves resided here, producing top-tier weapons and armor. Good thing I didn’t bring Frey… 

"I wish our country had mines like these…" 

"Wishing for what you don’t have won’t change anything." 

Leen shut me down instantly. Yeah, yeah, I know. 

Naturally, I couldn’t tell the subtle differences between ores just by looking. And unless it was something obvious like fossils or magic stones, [Search] wouldn’t pick them up either. 

If they were in obvious forms—like mithril golems or orichalcum golems—then sure. Speaking of which, I might’ve overhunted orichalcum golems when making Suu’s Ortlinde Overlord… To the point they nearly became endangered. 

When the other kings found out, they chewed me out. Well, it was like stealing valuable resources from other nations. 

To make amends, I had to share the locations of a few mithril and diamond golem habitats with the countries I’d inconvenienced. 

"That aside, you’re buying a lot. Do you really need this much for one Over Gear?" 

"It’s necessary! I can’t explain in detail, though." 

"Really? You’re not secretly adding your own share to the order, are you?" 

"Okaa-sama, doubting your own daughter is rather cruel, don’t you think? Ah, this one’s usable too! Otou-sama, let’s take this as well!" 

Dodging Leen’s suspicious gaze, Kuhn kept pointing out more steel. 

This is way too much… Even combined with the stockpile back at the Workshop, this is excessive. 

I knew Over Gears were larger than Frame Gears, so I’d braced myself, but… Will I even have enough money? Coming here to get a discount only to end up paying more would be ridiculous. 

With a hint of unease, I followed the mother-daughter duo. 

◇ ◇ ◇ 

"This is an enormous quantity… I’m curious what you need it all for, but I suppose I won’t pry." 

The Iron King looked astonished as he reviewed the list of items I’d stored in [Storage]. I’m astonished too. It’s over twice what I’d expected. Do you really need this much? How many units are you planning to make? 

Is she planning to build not just Over Gears but also a few underwater Frame Gears? 

Kuhn just smiled without explaining. Like the Doctor, people in her field are way too secretive. I’m the sponsor here, you know? 

"Now, about the payment…" 

"H-how much?" 

I gulped as the Iron King swiftly wrote down a number and handed me the paper. 

Huh? Wait, this is cheaper than I thought. Really? This amount? 

"Um, this seems incredibly discounted…" 

"Indeed. Actually, this relates to the favor I mentioned over the phone… If you’re willing to handle that, I’ll slash the price by half again." 

Ah, so there’s the catch. What exactly do you want me to do? 

"Take a look at this map." 

A map of Gandiris and its surroundings was spread across the reception table—clearly made from the smartphone maps I’d provided. The capital sat at the center. 

"Here’s Melcurium, the city with our largest mine. The Gandra Mountain Range separates it from the capital. To transport steel to the capital, we either cross the mountains via airship or take a long detour through this southern town." 

Hmm… Transporting steel by airship sounds unrealistic. Those things can’t carry that much weight, right? They’d never get off the ground. 

The southern detour isn’t great either—it’s way out of the way. Ah. I think I see where this is going. 

"What? You want me to dig a tunnel here?" 

I tapped the mountain range between the capital and Melcurium. The Iron King grinned, pleased I’d caught on. 

"Straight to the point, yes. We’ve always wanted a tunnel here, but the ground’s unstable in several areas. Digging recklessly would risk collapses, so it was too dangerous. But now that magic has spread from the eastern continent, I’m thinking earth magic could make it possible." 

Makes sense. Earth magic could reinforce unstable sections as we dig—like the shield tunneling method. 

"But this is really long…" 

When laying magi-rail tracks, I dug a tunnel through the mountains between Belfast Kingdom and the Refreese Empire, but this one’s nearly twice as long—close to 100 kilometers. I could do it, but I’d rather not spend too much time… Maybe I’ll just power through in one go. 

"Alright. I’ll do it." 

"Wonderful! You’ll take the job?" 

"Where exactly should I dig from and to?" 

"Ideally, the shortest straight path between the capital and Melcurium." 

As the Iron King and I discussed over the map, Leen elegantly sipped tea with the Queen and other royal ladies. As a Duchess herself, she carried herself with proper decorum to avoid embarrassing our nation. 

The problem was… 

"Ohhh, they’ve even routed ether lines into the drive system…! Aah! I see, it switches to auxiliary power here in emergencies—fascinating!" 

The problem was the Duchess’ daughter, currently attached to one of the royal guard golems stationed in the room, peeking into its joints. Well, the Gandiris folks probably think she’s just a relative’s kid, not an actual princess. 

The golem, stoic as a statue, didn’t so much as twitch as Kuhn clung to it. 

"Uh… Sorry about that." 

"Ah, no, no. I’m honored she finds our golems interesting." 

The Iron King responded with a strained smile as I apologized. Yeah, he’s totally exasperated. 

"These royal golems really use top-grade lubricant! Oh? This wiring here is—" 

Hey, maybe ease up? Her mother’s temple is starting to throb over there. Oops, too late. 

Leen excused herself with a "Do pardon me" and strode straight toward Kuhn. Yikes, she’s done for. 

Oblivious, Kuhn remained engrossed in the golem—until Leen’s fists drilled into her temples from behind. 

"Mmm, the friction coefficient here could—GYAAAH!? O-Okaa-sama!? That hurts!?" 

"Khuuun~? Care to explain yourself? Do you enjoy humiliating me?" 

Grind grind grind— Leen’s trademark Temple Drill erupted in full force. Pola trembled nearby, muttering "Terrifying…!"

"Uh… Sorry again." 

"Ah, well…" 

The Iron King didn’t even bother hiding his twitching smile this time. 

After confirming the tunnel route, I snapped reference shots of the direction and distance with my phone. Might as well plan for magi-rail tracks too—this’ll make future transport way easier. 

"Darling, we’ll help dig the tunnel too." 

"Eh? Okaa-sama, me too?" 

"You’re partly responsible for this, so yes." 

"Fiiine…" 

Freshly liberated from the Temple Drill, Kuhn replied weakly—probably fearing a repeat performance. 

Like Leen, Kuhn could use all non-dark magic. With both of them handling earth magic, the digging would go much smoother. 

Alright, time for a family excavation project! 

◇ ◇ ◇ 

"[Earth, Pierce—Spiral Excavation: Dig Spiral]!" 

""[Earth, Come—Rampart of the Land: Earth Wall]!"" 

As I boarded a 10-meter-wide horizontal tunnel, Leen and Kuhn—positioned on either side—reinforced the walls with [Earth Wall] to prevent collapses. The excavated dirt was compressed into dome-shaped walls and flat flooring. 

Once stabilized, we’d [Teleport] ahead and repeat the process. Each round covered about 10 kilometers, so ten trips should get us through. 

"We’ll need barrier magic after this, or monsters might invade." 

Otherwise, it’d just become a straight-line dungeon—with no escape routes. Gandiris definitely wouldn’t want that. 

"We should add rest areas along the way too!" 

"And ventilation shafts." 

Since golem-drawn carriages moved at 20–30 km/h, travelers would spend hours inside. Rest stops were a must. 

Once we’re halfway, I’ll carve out a wider space and add small vertical shafts for airflow. 

"Staying in a tunnel this long makes me feel like a mole or something…" 

"Oh darling, dwarves live like this all the time! Though they’re usually digging for ores." 

"If we hit a vein, maybe we can get more discounts on steel!" 

Just as I muttered that, the ground bulged—and a giant mole with razor-sharp claws burst through! Pola yelped and clung to Leen’s leg. 

"My, how rare. A Giant Mole. They’re here too?" 

"This is Otou-sama’s fault for jinxing it." 

"My fault?" 

The mole was probably drawn by the digging noises—not our conversation. Probably. 

"GGRRROOOAAARRGH…!"

The Giant Mole crawled out, claws raised threateningly. Hmm… Maybe it did hear us and mistook us for prey. 

Now, how to handle this— 

"[Water, Come—Pure Blade: Aqua Cutter]." 

"Ah." 

"GYOOOAAAGH!?" 

Before I could decide, Kuhn’s spell sliced the 5–6-meter-tall mole clean in half. Yikes. 

"Honestly… Think before you cast, dear." 

"Huh? Fire magic’s risky here, so water was best, no?" 

"True, but how you kill matters. Even if Darling stores it in [Storage], the bloodstains’ stench won’t disappear." 

Sure enough, the tunnel reeked of copper. Really, really bad. 

I quickly stored the mole’s remains and used wind magic to push the tainted air out. 

"Water magic to drown or ice magic to freeze would’ve been better." 

"Ugh… Next time, then." 

Leen patted Kuhn’s slightly pouting head—probably a reflexive gesture. Kuhn was smart enough to realize it herself if she’d thought a bit longer. 

A few more giant moles and worms appeared, but Kuhn froze them solid this time. 

There’s a lot down here… Once done, we’ll need reinforcement and barrier magic to keep them out. 

As I activated [Dig Spiral] again, something felt off—like the spell had punched through empty space. 

Huh? Did we break through? But we’re nowhere near the other side… 

"Feels like there’s a hollow space…?" 

"Oh? Did we hit a cavern?" 

The tunnel was dark, lit only by Leen’s floating [Light]. Even its glow didn’t reach the newly opened hole ahead. 

Kuhn created another [Light] and rushed toward the breach. Hey! No running off—we don’t know what’s in there! 

"This is—! Otou-sama! Okaa-sama! Look!" 

"What? What’s there?" 

At Kuhn’s shout, Leen and I hurried over. 

"Wha—!?" 

Beyond Kuhn’s [Light], a faint glow—like luminescent moss—illuminated the space. 

And what we saw was… 

A massive city sprawled below. 

Faintly visible were streets, buildings, and even distant towers and pyramid-like structures. A full-fledged underground city—or rather, ruins. 

Most structures were partially collapsed, clearly ancient. Who’d have thought tunneling would lead us here? 

"This is amazing! Even in the future, this place was never discovered! A huge find!" 

"We’ve dug up something incredible. Maybe we’ll get our steel for free now?" 

"Sweet. Let’s splurge on dinner later." 

While Kuhn buzzed with excitement, Leen and I traded jokes—though privately, I did feel like we’d stumbled into trouble. 

"Never discovered in the future"? Did the timeline change? Or did future Gandiris hide this city? What’s going on? 

I called the Iron King, who—just as excited as Kuhn—declared he’d come immediately before abruptly hanging up. 

Uh, "immediately" by airship still takes time… Should I fetch him? Nah, if he says he’s coming, we’ll wait. An hour or two, tops. 

"Otou-sama! Let’s investigate! We need to check for dangers!" 

And now the problem. I highly doubt I can restrain this overexcited girl until the king arrives. 

Still, a safety check was necessary. This could be a nest for underground monsters like those Giant Moles. 

Following Kuhn’s lead, we descended through the breach. The outer wall had crumbled into a cliff-like drop, but [Fly] got us down safely. 

The central plaza’s cobblestones were cracked, buildings partially collapsed. Definitely ruins. 

"Without preservation magic, the damage is severe. Golems last ages, but structures don’t." 

"Probably couldn’t protect an entire city like our magic." 

According to the Doctor, ancient magic civilizations often reinforced buildings with earth magic or preservation spells. 

This continent had the technology but never widely adopted it. Only valuables got preserved. 

Which means… there might be treasure here? 

Okay, now I was getting excited—until a loud CLANG echoed through the ruins. 

"…What was that? Something’s here." 

More metallic clanks followed. We tensed, ready to act. 

The sounds multiplied until, from the dim glow, a golem emerged. 

Human-sized, clad in brass armor like a knight—but its "face" was a single camera-like lens darting side to side. Definitely mechanical. 

Four pipes protruded from its back, emitting glittering steam, with more leaking from its joints. It looked one step from breakdown. 

And it wasn’t alone. More brass golems shambled from the ruins, closing in. Though unarmed, their eerie advance felt zombie-like. 

"An underground city of golems, huh…" 

"Darling, what now? Wipe them out with wide-range magic?" 

"What!? Okaa-sama, those are precious Legacy units! Destroying them might be irreversible!" 

"…My own daughter is such a hassle." 

Leen sighed as Kuhn clung to her. I get it—they’re valuable. But if they attack, we can’t hold back. 

Kuhn clung tightly to me, and Leen let out a sigh that sounded like it came from the very depths of her soul.I mean, I get it—those golems are valuable. But if they’re going to attack us, I’m not going to hold back.

…Though, since it’s Kuhn’s request, maybe I’ll just shut them down without breaking anything.

If I freeze them solid, I can probably avoid damaging them.

Just as I was about to activate my freezing seal magic—【Eternal Coffin】—a woman’s voice suddenly echoed through the underground city.

『Everyone, stand down. I will not allow you to harm these people.』

The sudden voice caught us all by surprise. The brass golems slowly backed away to either side, creating a path, just like that one famous scene from the Ten Commandments.

And at the end of that path, she appeared.

She wore a flowing white garment—just like a toga from ancient Rome. Her long hair shimmered like silver, and her golden eyes sparkled in the dim light. Amidst the darkness, her beauty seemed to shimmer with an almost otherworldly glow.

“Welcome to the Machina City—Agartha.Children of the surface.”

The silver-haired woman in the toga smiled gently as she spoke to us in the heart of the underground city.