The Yandere villainess loves the useless engineer

The battle against the magic beast marked a turning point in the operation.

After its death, the remaining rats became noticeably less organized.

The endless coordinated swarms stopped.

Large groups still attacked occasionally during the following days, but nothing like before. Without the massive beast driving them crazy, the colony slowly began collapsing into scattered pockets hiding throughout the tunnels.

And for the first time since entering the mine—

The workers stopped looking constantly terrified.

Not comfortable.

Definitely not comfortable.

But no longer convinced they were moments away from being eaten alive every second underground.

The reclamation continued deeper and deeper into the mine over the following weeks.

Smoke constantly flowed through the expanding pipe system while workers extended the railway section by section farther underground. The steam engines operated almost nonstop now as minecarts rapidly moved supplies, tools, and workers throughout the reclaimed tunnels.

The atmosphere underground slowly changed as well.

The mine no longer felt like a monster nest.

It started feeling alive again.

Lanterns illuminated cleared passageways while reinforced supports replaced rotting beams in unstable areas. Fresh air from the oxygen pipes slowly pushed away decades of foul underground air while the rail system made movement dramatically safer.

Even the workers had adapted surprisingly quickly.

At first every distant scratching sound sent people sprinting toward the minecarts.

Now—

Most barely even reacted.

Because the hordes had changed.

The massive swarms of hundreds slowly became dozens.

Then smaller groups.

Eventually many tunnels contained only isolated rats hiding among deeper chambers and abandoned nests.

And once the workers realized the creatures no longer completely overwhelmed them—

Everything accelerated.

The rifles handled smaller groups easily.

The flamethrower became more of a terrifying insurance policy rather than the only thing keeping everyone alive.

Even Garrick started looking less tense underground.

Though the hunter still visibly hated the deeper tunnels.

One afternoon while workers cleared debris from one of the older collapsed sections, Finn wiped soot from his face before glancing around the illuminated tunnel.

"You know what’s horrifying?"

I adjusted part of the rail alignment nearby.

"What?"

Finn gestured vaguely around the mine.

"We’ve been here so long this place is starting to feel normal."

A nearby worker immediately nodded.

"That’s the worst part honestly."

Rowan meanwhile sat beside the flamethrower fuel tanks eating bread casually like he had not spent the last two weeks burning giant rats alive underground.

Garrick stared at him occasionally with visible confusion.

The hunter still clearly had not processed how quickly these people adapted to industrial extermination warfare.

By the second week we started reopening several tunnels originally collapsed during the first phase of the operation.

Now that the main colony had been broken apart, I wanted access to the deeper ore veins and underground chambers.

Controlled blasting replaced emergency collapses while workers carefully reinforced weakened sections using new timber and steel supports brought from Aldric territory.

And the deeper we went—

The more my suspicions became confirmed.

The soil quality underground was absurd.

Especially near older nest chambers.

Dark nitrate-rich earth coated entire lower sections of the mine after decades of rat occupation, waste buildup, decomposition, and moisture accumulation.

To me—

It practically looked like treasure.

To everyone else—

It looked like dirt.

Three weeks after the operation first began, Garrick finally stood beside me near the deepest cleared chamber while workers celebrated farther down the tunnel.

The mine was finished.

Completely reclaimed.

Rail systems now stretched throughout the main tunnel networks while ventilation pipes continuously pumped fresh oxygen deeper underground. Lanterns illuminated the major passages while minecarts rapidly moved between sections using the steam-powered cable systems.

The place barely resembled the death trap we originally entered.

Finn leaned against one of the rail carts while looking exhausted.

"...I never want to see another rat again."

One worker nearby nodded immediately.

"Agreed."

Another paused slightly.

"...Unless it’s already on fire."

Rowan looked oddly proud hearing that.

Garrick meanwhile slowly stared deeper into the mine.

For thirty years the place had remained abandoned.

Now workers casually moved through the tunnels carrying tools and supplies like normal miners again.

The hunter still looked half unable to believe it.

Eventually he glanced toward me.

"So what now?"

I looked around the chamber thoughtfully.

"Now we start extracting."

Garrick nodded slightly.

"There’s still decent iron down here."

Then he frowned slightly.

"Though honestly I’m surprised you went through all this trouble for iron."

I blinked once.

"I wasn’t after the iron."

That immediately confused the hunter. 𝓯𝓻𝒆𝙚𝒘𝓮𝙗𝓷𝒐𝓿𝙚𝒍.𝙘𝓸𝙢

"...What?"

I crouched slightly before grabbing a handful of dark soil from near one of the old nest chambers.

"This."

Garrick stared blankly.

"...Dirt?"

"Nitrate-rich earth."

That explanation somehow made Garrick even more confused.

I sighed softly before trying again.

"The soil absorbed waste and decomposition for decades."

I pointed deeper into the mine.

"Especially near the nests."

"...And that matters because?"

I hesitated briefly while thinking how to explain it without sounding completely insane.

"It’s useful for producing explosive powder."

Understanding slowly spread across Garrick’s face.

"...The black powder from your weapons?"

"Yes."

The hunter stared toward the dirt again.

"All this..."

His eyes slowly widened.

"...You came here for rat filth."

Finn immediately burst out laughing nearby.

"When you say it out loud it really does sound ridiculous."

I ignored him.

"The nitrate beds back in Aldric territory take months to produce enough usable material."

I gestured around the mine.

"This place already contains decades worth naturally."

Now Garrick finally understood why I became so obsessed with reclaiming the tunnels.

The hunter slowly looked around the massive underground system again.

"...You really saw value in a place everyone else abandoned."

I stood back up calmly.

"They saw a dead mine."

Then I looked deeper underground toward the dark soil lining the lower chambers.

"I saw gunpowder."

Silence lingered briefly afterward before I looked back toward Garrick.

"I’ll need workers."

The hunter folded his arms slightly.

"For the mine?"

"Yes."

I gestured toward the rail systems.

"The workers I brought with me need to return to the steel factory in Aldric territory."

The industrial district there still needed them desperately.

Especially now that steam engines, vehicles, weapons, and large-scale steel production kept expanding simultaneously.

Garrick rubbed his beard thoughtfully.

"A lot of people won’t believe we actually cleared the mine."

"That’s fine."

The hunter slowly smirked slightly for the first time in weeks.

"I’ll convince them."

I raised an eyebrow slightly.

"You sure?"

Garrick looked around the reclaimed tunnels again.

The lanterns.

The rails.

The fresh air systems.

The complete absence of shrieking monsters.

"...After what I just watched for three weeks?"

He gave a quiet laugh.

"Trust me."

Then the hunter looked toward the workers farther down the tunnel.

"Once people see this place themselves..."

His expression hardened slightly.

"You’ll have all the workers you need."

Two days later the remaining workers, Finn, and I finally departed from Blackwater Hollow.

This time the atmosphere felt completely different from when we first arrived.

Back then we entered the territory carrying rifles and explosives while everyone quietly wondered whether we were marching toward our deaths inside a monster-infested mine.

Now—

We left behind a functioning mining operation.

Smoke no longer poured from cursed tunnels filled with shrieking swarms. Lanterns illuminated reinforced passageways underground while steam-powered minecarts rolled through the reclaimed tunnels carrying debris and ore beneath fresh airflow pumped through my ventilation pipes.

Even the villagers looked at us differently now.

Not suspicious.

Not nervous.

Almost stunned.

Several miners from the village had already started cautiously entering the upper sections under Garrick’s supervision after finally accepting that the mine truly had been reclaimed.

Garrick himself stood near the wagons while watching workers secure the remaining equipment.

"Still can’t believe you actually did it."

I adjusted one of the rifle straps along my side.

"We almost died multiple times."

"Yet somehow that feels less important than the fact you won."

The hunter glanced toward the distant hills where the mine rested hidden behind the forests.

"For thirty years nobody could even enter that place safely."

Finn climbed onto one of the wagons while stretching tiredly.

"Turns out industrialized rat extermination is surprisingly effective."

Garrick slowly looked toward him.

"I still don’t fully understand half the things you people built."

"That’s probably healthier honestly."

Before leaving, Garrick handed me several folded papers containing names from villagers interested in working the mine now that it had become safe again.

"Once word spreads farther, more people will come."

I nodded slightly.

That was good.

Very good.

The upper chambers alone contained enough nitrate-rich soil to completely change the scale of my gunpowder production.

And now that the mine had ventilation systems, rails, steam-powered carts, and reinforced tunnels—

Extraction would only become easier over time.

The journey back toward Aldric territory took several days mostly because everyone looked half dead from exhaustion.

Even Rowan spent most of the trip asleep beside the flamethrower fuel barrels while several workers quietly debated whether the giant magic rat actually happened or if exhaustion had collectively damaged their minds.

Finn eventually looked toward me from the front wagon.

"You know the concerning part?"

"What?"

"We’re becoming used to this."

I glanced toward him slightly.

"We fought giant rats underground using steam engines and fire."

"Exactly."

Finn pointed dramatically.

"And somehow that no longer feels weird enough."

As the group finally approached Aldric territory again, the industrial district immediately came into view beyond the roads.

And somehow—

It had grown even larger during my absence.

New workshops stood beside expanded foundries while thick smoke continuously rose from the steel factory district farther away from the original shack. Waterwheels turned steadily beside mechanical hammers while workers transported steel beams, tools, and machinery between buildings.

The entire area felt alive.

Busy.

Industrial.

Finn stared ahead proudly.

"We built this."

I slowly looked across the growing district.

The original shack that once barely produced crude prototypes now stood at the center of an expanding industrial zone.

And now—

The nitrate problem was solved.

That single realization changed everything.

The moment I stepped down from the wagon my mind immediately started moving ahead again.

"We need refining stations in Blackwater Hollow."

Finn groaned instantly.

"We JUST got back."

I ignored him completely.

"There’s no point transporting raw nitrate-rich soil all the way here when we can process most of it near the mine itself."

I continued walking while thinking aloud.

"We’ll build extraction facilities there and produce gunpowder directly inside Blackwater Hollow."

Finn slowly blinked.

"...You’re mass producing explosives now."

"Yes."

"That sentence should concern me more than it already does."

My eyes moved toward the distant steel production district.

"We also need reliable transportation between the two territories."

That part was becoming obvious now.

Blackwater Hollow sat entirely enclosed inside Nightbane territory several hours away from Aldric lands. Transporting steel, machinery, gunpowder, and refined materials using wagons alone would quickly become too slow once production expanded.

Especially during wartime.

I stopped walking suddenly.

Finn immediately noticed the look appearing across my face.

"...No."

I slowly smirked.

"We already have rails."

Finn’s expression immediately shifted toward horror.

"...Leon."

"We already understand steam engines."

"Leon."

"And now we have reason to connect long-distance industrial centers."

Finn physically stepped backward slightly.

"No."

I turned toward him fully now.

"We’re going to make a train."

Silence.

Nearby workers slowly stopped what they were doing after overhearing that sentence.

One worker frowned slightly.

"...What’s a train?"

Finn pointed toward me immediately.

"Something terrible probably."

But I barely even heard him anymore.

My mind already raced ahead.

Larger steam engines.

Rail networks.

Cargo transport.

Steel lines stretching across territories.

Industrial supply chains.

The war with the Magneto Kingdom still continued.

And while kingdoms fought using magic and medieval armies—

I was already thinking about rail infrastructure.