The Yandere villainess loves the useless engineer

The next morning, snow lightly drifted outside the workshop while the blast furnace continued rumbling in the background like a sleeping giant.

Inside the renovated shack, I sat hunched over a desk covered in papers and charcoal sketches.

Steam engine designs.

Cylinder layouts.

Pressure systems.

Rotational transfer mechanisms.

Even with all my knowledge from my past life, creating a functioning steam engine from scratch using medieval-level tools was going to be absurdly difficult.

Still—

Now that we had access to molten iron, it was finally possible.

Lilith meanwhile sat directly beside me with her chin resting against my shoulder while staring at the sketches with visible disappointment.

"...This is boring."

"It’s engineering."

"It’s ugly."

I ignored her and continued sketching piston movement.

Lilith sighed dramatically before wrapping her arms around my neck from behind.

"You know what would be easier?"

"What."

"You abandoning all this and coming to live with me in the NightBane territory."

"No."

"You didn’t even think about it."

"Because the answer is still no."

Lilith pouted slightly.

"We could live in a giant manor together."

"No."

"You could sleep in my room."

"...Definitely no."

"You’re impossible."

I smirked slightly while continuing my design.

She had been pestering me nonstop ever since arriving.

At some point, she had apparently decided my industrial revolution was less important than becoming her husband.

A loud knock suddenly echoed through the shack.

Finn stepped inside brushing snow off his coat.

"You’re both awake already?"

Lilith immediately narrowed her eyes at him suspiciously.

Finn pretended not to notice.

Those two still terrified each other.

Finn walked further inside before looking toward me.

"Leon, there’s someone in town asking about the steel."

I barely looked up from my sketch.

"Then ignore them."

"That’s what I usually do."

We’d already had several merchants attempt to secure exclusive deals with us after hearing about our steel quality.

I had rejected every single one.

Selling smaller quantities anonymously was far safer.

The less attention we attracted, the better.

But Finn hesitated slightly.

"This one’s different."

That made me pause.

"...How?"

Finn scratched the back of his head awkwardly.

"He’s from the Valmere Trading Family."

My charcoal pencil immediately stopped moving.

Lilith also blinked slightly.

The Valmere family.

Even I recognized that name.

They weren’t just merchants—

They were practically an economic empire within the Kingdom of Magneto.

Caravans.

Shipping routes.

Ports.

Warehouses.

They controlled absurd amounts of commerce across the kingdom.

A minor barony like ours normally wouldn’t even get noticed by people like that.

I slowly leaned back in my chair.

"...Why are they interested in us?"

Finn crossed his arms.

"Because our steel is weird?."

Fair enough.

Compared to ordinary medieval steel production, ours was absurdly refined.

Most blacksmiths in this world created inconsistent steel with varying impurities because they lacked proper temperature control and airflow regulation during smelting.

Meanwhile—

We carefully controlled carbon content through repeated heating cycles while using continuous airflow from the waterwheel bellows to maintain stable temperatures.

The result was cleaner, stronger, and more flexible steel with far fewer weaknesses.

To local blacksmiths, it probably looked almost magical.

Lilith glanced toward me smugly.

"Or you could just use my magic."

"No."

Finn sighed.

"You two are hopeless."

————

A while later, the three of us arrived in town.

Near the market square stood a well-dressed older man wearing a dark fur-lined coat with silver embroidery stitched into the sleeves.

The moment he spotted us, his eyes immediately landed on the steel bar Finn carried.

"So these are the young smiths I’ve heard so much about."

"We’re not smiths," I replied automatically.

The merchant smiled politely.

"My apologies. Inventors, perhaps?"

That made me narrow my eyes slightly.

Smart.

Very smart.

He already understood this wasn’t normal blacksmith work.

"My name is Cedric Ross ," the merchant introduced himself. "Representative of the Valmere Trading Family."

Finn looked visibly nervous standing beside me.

Meanwhile Lilith looked completely uninterested and instead continued petting Potato.

Cedric carefully inspected one of the steel bars before speaking again.

"I’ve visited nearly every forge in the eastern territories."

He lightly tapped the steel.

"And yet none produce material remotely comparable to this quality."

I remained silent.

The merchant continued calmly.

"The structure is unusually consistent. Minimal impurities. Strong yet flexible."

His eyes slowly lifted toward me.

"This level of refinement should not be possible in a border barony."

That sentence alone told me this man was dangerous.

He noticed too much.

Still—

If the Valmere family truly became interested in us...

That could accelerate everything.

Cedric suddenly smiled again.

"My employer would like to meet you personally in the royal capital."

"I’m not interested," I replied immediately.

Traveling to the capital sounded exhausting.

Not to mention dangerous.

Cedric remained calm.

"My employer is Lady Seraphina Valmere."

That name sounded vaguely familiar.

One of the highest-ranking figures within the trading family if I remembered correctly.

"She specifically requested the creator of this steel."

I opened my mouth to refuse again.

Then suddenly—

Lilith’s arms wrapped around my shoulders from behind.

"He would be happy to."

I froze.

"...Lilith."

Cedric immediately smiled brightly.

"Excellent."

"I did not agree."

"You were about to."

"No I wasn’t."

Lilith ignored me completely.

Cedric gave a respectful bow before reaching into his coat and handing me a sealed card.

"If you arrive in the royal capital, ask for Lady Seraphina Valmere at the Grand Meridian Commerce Hall."

He smiled slightly.

"She’ll be very interested in meeting you."

Then, without another word, the merchant departed into the crowded streets.

Meanwhile—

I slowly turned toward Lilith.

"...Why."

Lilith smiled innocently.

"Because now you’re coming to the capital with me ."

Lilith happily clasped her hands together.

"My winter break ends in a couple days," she explained cheerfully. "So I’ll be returning to the academy soon."

A horrible feeling began creeping into my chest.

"And?"

"And you’re coming with me."

"No I’m not."

"Yes you are."

"I absolutely am not."

Lilith ignored my resistance completely.

"You can stay at the NightBane manor in the capital."

"I don’t want to."

"You can show me more weird inventions."

"No."

"And we can spend every day together."

"...That sounds exhausting."

Lilith immediately tightened her grip around my shoulders.

"Too late."

Finn looked between the two of us before slowly backing away.

"...I’m not getting involved in this."

Smart man.

————

The next two days passed in complete chaos.

With my upcoming trip to the royal capital rapidly approaching, I spent nearly every waking moment preparing the workshop before leaving.

Finn stood beside me near the bloomeries while I aggressively pointed at various things like a sleep-deprived manager preparing an employee for disaster.

"Keep the airflow consistent."

"Got it."

"Don’t overfill the furnace."

"Got it."

"Watch the carbon ratios carefully."

"Got it."

"And if anything breaks—"

"It’s my fault. Yes, I know."

I narrowed my eyes.

"I’m serious."

"So am I."

Leaving the workshop behind made me more nervous than traveling to the capital itself.

The bloomeries were one thing.

But now we had a functioning blast furnace.

And a frame steam engine design sitting in the shack.

One mistake could ruin months of progress.

Finn meanwhile looked far less worried.

Mostly because he apparently had complete faith in my insanity.

"...You’ll be fine," he said while leaning against the cart. "Just try not to get kidnapped by nobles."

"That’s oddly specific."

"You attract problems."

Fair enough.

I sighed before glancing around the clearing one final time.

The furnaces.

The waterwheels.

The workshop.

Honestly—

Seeing how much this place had changed over the last year felt surreal.

It was no longer just some abandoned shack in the woods.

It was the beginning of something far bigger.

Eventually I looked back toward Finn.

"Just focus on steel production while I’m gone."

Finn nodded.

"Same process as usual?"

"Yeah. Prioritize quality over quantity."

"Got it."

I hesitated briefly before adding—

"And don’t let anyone suspicious near the workshop."

Finn snorted.

"After seeing what your girlfriend did to me?"

"She’s not my girlfriend."

"Sure."

I ignored him completely.

————

By the time I returned to the manor, the sky had already begun darkening.

The moment I entered the house, my mother immediately noticed the travel bags in my hands.

Her expression shifted instantly.

"...Leon?"

"I’m going to the capital."

Silence.

Then—

"The capital?"

She slowly placed down the book she had been reading.

"Why?"

I immediately regretted opening my mouth.

Trying to explain any of this sounded ridiculous.

After several minutes of interrogation, however, I eventually ended up explaining part of it.

The steel.

The workshop.

The bloomeries.

The blast furnace.

Although—

I very intentionally skipped over the nitrate beds.

Some secrets needed to remain secrets.

My mother stared at me in complete shock after I finished speaking.

"...You built all of that?"

"...Maybe."

"Leon."

"...Yes."

She placed a hand against her forehead.

"I thought you were just wandering around the forest every day."

"I mean technically I was."

"Wait..."

She looked directly toward me.

"Your father has been trying to contact the people producing that steel."

I blinked.

"...What?"

She nodded quickly.

"He heard rumors from knights and merchants about unusually refined steel appearing in nearby markets."

Apparently even the border forces had begun noticing differences in durability and weapon quality.

"He wanted to place private orders personally."

That honestly caught me off guard.

I had expected merchants to notice eventually.

But my father?

That complicated things slightly.

Still—

I could deal with that after returning from the capital.

Probably.

Hopefully.

Maybe.

————

The next morning arrived quickly.

Before sunrise, several black carriages bearing the NightBane crest stood outside the manor prepared for departure.

Snow covered the roads while cold wind swept across the territory.

Lilith meanwhile looked far too happy.

She had been excited nonstop ever since learning I was coming with her.

The moment she spotted me exiting the manor with my bags, she immediately walked over and grabbed my arm possessively.

"You’re finally coming to the capital with me."

"You say that like I had a choice."

"You didn’t."

Fair enough.

My parents stood nearby saying their goodbyes while servants loaded supplies into the carriages.

My mother still looked deeply concerned about the entire situation.

Meanwhile my father simply looked confused.

Mostly because he still had absolutely no idea his son secretly operated illegal industrial projects in the forest.

Probably for the best.

Eventually, after everything was prepared, we departed from the Aldric territory.

The journey lasted several days.

Snow-covered forests gradually turned into larger roads crowded with merchants, travelers, and noble carriages the closer we approached the capital.

And finally—

The royal capital came into view.

Massive walls towered above the horizon while countless buildings stretched beyond them beneath the winter sky.

Even from a distance, the city looked enormous.

Alive.

At the center of it all stood the royal palace shining above the capital like a symbol of absolute authority.

Meanwhile beside me—

Lilith smiled proudly.

"Welcome to the capital, Leo."

Not long afterward, the NightBane carriage passed through the city gates before eventually stopping in front of an enormous manor deep within the noble district.

Black iron gates.

Snow-covered gardens.

Towering architecture lined with silver and dark stone.

The NightBanes capital manor.

And apparently—

My new home for the next couple days.

I stepped out of the carriage slowly while staring up at the massive estate.

Everything about the capital felt overwhelming.

Meanwhile beside me, Lilith stepped down from the carriage with a faint smile on her face.

Then she looked toward me.

Her deep purple eyes gleamed slightly before she wrapped her arms around one of mine possessively.

"You can’t escape me now, Leo."

I immediately sighed.

"...I was afraid you’d say that."