The Yandere villainess loves the useless engineer

Several days later—

I finally returned to the Aldric territory.

Honestly—

The moment the carriage crossed back into the snowy familiar lands, I felt strangely relieved.

The capital was exhausting.

Mostly because of one specific black-haired menace.

Eventually the carriage rolled through the gates of the Aldric manor before coming to a stop.

I stepped outside stretching slightly after the long trip.

Then immediately—

"Leon!"

My mother quickly walked down the manor steps toward me with visible relief.

"You’re finally back."

I smiled slightly.

"Yeah."

She immediately pulled me into a quick hug before stepping back and looking me over carefully.

"...Where’s father and Alex?" I asked after noticing the manor felt quieter than usual.

My mother’s expression shifted slightly.

"They’re dealing with border matters."

"...Border matters?"

She nodded slowly.

"There’s been rising tension with the neighboring kingdom recently."

Her voice became more serious.

"Trade disputes. Territorial arguments. Military movement near the border."

I frowned slightly.

"And?"

"...It’s likely war may break out within the next few months."

That immediately caught my attention.

War.

Honestly—

That was bad timing.

Very bad timing.

Especially considering I was currently building industrial technology inside a medieval fantasy world.

Still—

There wasn’t much I could do about it right now.

After speaking with my mother a little longer, I eventually left the manor and headed toward the forest shack.

Or rather—

What used to be a shack.

At this point it honestly looked more like a proper workshop complex.

Smoke rose from the bloomeries while the waterwheels slowly turned beside the river.

The moment I arrived, I spotted Finn near the furnaces tending the flames.

He looked up after hearing footsteps.

Then immediately grinned.

"Leon!"

"Finn."

Honestly—

It felt good being back.

The moment I approached, Finn immediately started asking questions about the capital and the merchant deal.

So naturally—

I told him the price Lady Seraphina Valamere agreed paying for the steel.

The moment I finished speaking—

Finn froze completely.

"...Wait."

Then his eyes widened.

"...Per ingot?"

"Per ingot."

Silence.

Then—

"ARE THEY INSANE?!"

Finn nearly dropped the steel tongs in his hands.

"That much money for ONE?!"

Honestly—

His reaction was reasonable.

Even I still thought the numbers sounded ridiculous.

Finn grabbed both sides of his head dramatically.

"We’re rich."

"Not yet."

"LEON WE’RE RICH."

Honestly—

Fair point.

After Finn finally calmed down slightly, I asked the important question.

"So. Anything go wrong while I was away?"

Finn shook his head.

"Not really."

Then he paused slightly.

"Though..."

"Hm?"

"That weird manure pit thing."

"The nitrate bed."

"Yeah that."

Finn pointed toward the distant covered pit area.

"There were weird salt-like crystals forming in it."

For a moment—

I just stared at him.

Then slowly—

A grin spread across my face.

Finn looked confused immediately.

"...Why are you smiling like that?"

"That’s amazing."

"...What?"

I immediately started walking toward the nitrate bed excitedly.

Finn quickly followed behind looking completely lost.

Honestly—

If crystals were already forming this early—

Things were progressing even faster than expected.

And if I was right—

The next stage of Leon Aldric’s industrial revolution was finally about to begin.

Finn spent the next several weeks tending the nitrate beds almost like they were crops.

Every morning he carefully turned the rotting mixture with a shovel while Leon occasionally inspected the strange white crystal growth forming within certain sections of the bed. The smell was absolutely horrific, especially once the warmer days arrived, but Leon insisted the process was working perfectly.

Water was filtered slowly through layers of ash, earth, straw, and aged waste before being collected inside large barrels near the workshop. Afterward the liquid was heated and refined repeatedly while Finn grumbled the entire time about how he went from being a blacksmith assistant to apparently becoming a farmer for glowing dirt water.

Over time, pale salt-like crystals slowly began forming in the drying trays Leon had prepared. The moment Leon saw them, his eyes practically lit up with excitement while Finn just stared in confusion at the tiny white flakes that had apparently consumed months of effort.

To Finn, they looked worthless.

To Leon—

They were the foundation of a weapon that could one day shake kingdoms.

Over the next few days, Leon and Finn prepared several fresh ingots of refined steel for sale.

The workshop remained busy from morning until night as the bloomeries roared constantly beside the river while the waterwheels steadily powered the bellows without pause.

At this point, producing steel had become far smoother than when they first started months ago.

The carbon ratios were more controlled.

The impurities were lower.

And the consistency between ingots had improved massively.

Even Finn—who once barely understood what Leon was doing—could now identify flaws within steel by sight alone.

Eventually, once enough ingots were prepared, the two loaded them carefully onto the cart behind Potato before heading toward town.

The moment they arrived near the merchant district, they quickly spotted a familiar carriage bearing the emblem of the Valamere Trading Corporation.

Beside it stood Cedric Ross.

The sharply dressed merchant immediately smiled upon noticing Leon and Finn approach.

"Master Leon," Cedric greeted politely.

Honestly—

Hearing people call him "Master" still felt strange.

Finn meanwhile looked incredibly smug hearing that.

The steel ingots were carefully unloaded one by one while Cedric inspected them thoroughly.

As expected—

The merchant’s expression only became more impressed.

"Incredible consistency once again," Cedric muttered while examining one of the ingots closely beneath the sunlight.

"Most smiths can barely maintain this quality across a single blade, yet you produce it repeatedly."

Leon simply shrugged slightly.

Meanwhile Finn looked like he wanted to brag for an hour straight.

Eventually the deal was finalized.

Cedric handed over a heavy pouch filled with coins.

The moment Finn felt the weight—

His eyes widened.

The amount of money felt unreal.

A single small gold coin per ingot.

Honestly—

It was enough money to completely change both their lives.

Just as Cedric prepared leaving though, Finn suddenly spoke up.

"Wait."

Cedric paused.

"Yes?"

Finn glanced toward Leon briefly before asking,

"Do you happen to have any sulfur?"

Cedric blinked slightly.

"Sulfur?"

"A yellow mineral," Leon added casually. "Used occasionally by alchemists."

The merchant looked thoughtful for a moment before nodding.

"I only carry small quantities currently."

Then he motioned toward one of the carriage workers, who returned moments later carrying several wrapped bundles.

A faint unpleasant smell immediately followed them.

Finn grimaced.

"That smells awful."

"It’s sulfur," Leon replied simply.

Cedric handed over the bundles before speaking again.

"If you require larger amounts, I can arrange it by my next visit."

That immediately caught Leon’s attention.

"How much larger?"

Cedric smiled faintly.

"The Valamere Corporation can acquire most things in quantity."

Honestly—

That was an extremely useful connection to have.

Leon nodded.

"That would help."

Cedric gave a polite bow before returning toward his carriage.

"Then I shall inform Lady Seraphina."

Not long afterward, Leon and Finn departed town once again with:

- fresh money,

- new supplies,

- and several bundles of sulfur loaded onto the cart beside them.

As Potato slowly carried them back toward the forest workshop, Finn glanced toward the sulfur suspiciously.

"So..."

He frowned.

"What horrifying thing are we making next?"

Leon simply grinned slightly while staring ahead toward the distant workshop.

Honestly—

The next stage was about to begin.

By the time Leon and Finn returned to the workshop, the sun had already begun setting behind the snowy trees.

The cart creaked softly as Potato dragged it toward the shack while smoke continued rising from the bloomeries nearby.

Several sacks of charcoal sat beside the sulfur and refined nitrate crystals.

Finn stared at all three materials suspiciously.

Then slowly looked toward Leon.

"...You’re smiling again."

Leon ignored him completely.

Instead he immediately began organizing everything across the workshop tables with unusual focus.

The atmosphere itself started feeling different.

More serious.

Even Finn could sense it.

For the next several hours Leon worked carefully while Finn assisted despite having absolutely no understanding of what Leon was attempting create.

The strange mixture was refined repeatedly.

Ground down.

Filtered.

Adjusted.

Leon tested tiny amounts several times while muttering calculations beneath his breath.

Twice small flashes startled Finn badly enough that he nearly threw a hammer across the room.

"LEON!"

"I said be careful near it."

"YOU SAID THAT AFTER IT EXPLODED!"

"It barely exploded."

Finn stared at him in disbelief.

Eventually—

Late into the night—

Leon carefully poured a small amount of black powder-like material across a flat stone surface.

Then he stepped back silently.

Finn watched cautiously.

"...That’s it?"

Leon slowly nodded.

Honestly—

Even he felt slightly nervous.

After all—

This was the first time he had recreated something this dangerous within this world.

Leon carefully reached forward with a burning splint.

Then touched the powder.

For half a second—

Nothing happened.

Then suddenly—

FWOOOM.

A violent flash erupted instantly alongside a thunderous crack that echoed through the forest.

The explosion startled birds from distant trees while smoke burst outward across the workshop.

Finn immediately stumbled backward in shock.

"What in the hells WAS THAT?!"

Leon stared silently at the scorched stone.

The powder was gone.

Completely gone.

Only black burn marks remained behind.

Slowly—

A grin spread across Leon’s face.

Because sitting before him was not magic.

Not mana.

Not some mystical artifact.

It was science.

And in that moment—

Leon realized he had just created something capable of changing warfare forever.