The Yandere villainess loves the useless engineer

The next several hours were spent hammering.

Endless hammering.

Painful hammering.

The glowing bloom rested atop a large stone slab while Finn and I took turns repeatedly striking it with heavy hammers.

CLANG!

Sparks exploded outward.

CLANG!

More slag and impurities broke away from the metal.

CLANG!

Finn wiped sweat from his forehead before glaring at the steel angrily.

"How is this not done?"

"Because you hit like an old man."

"I’m literally using both hands!"

I grinned slightly before reheating the metal within the furnace again.

That became the process for the rest of the day.

Heat.

Hammer.

Fold.

Repeat.

Again and again.

Each cycle compressed the steel further while forcing more impurities out from the metal.

Honestly?

The final result looked nothing like the rough bloom we originally extracted from the furnace.

Now the steel appeared darker.

Denser.

Cleaner.

Even Finn, who knew almost nothing about metallurgy, could tell the difference immediately.

"...It looks expensive," he muttered while staring at the finished chunk resting atop the worktable.

That was because it probably was.

I carefully ran my fingers across the cooled metal surface.

It wasn’t perfect.

Not even close.

Compared to modern steel, this was still primitive.

But compared to what existed in this world?

It was leagues ahead.

And more importantly—

It proved the process worked.

I smiled slightly.

"This changes everything."

————

The following morning, Finn and I wrapped the steel carefully in cloth before heading toward town.

The chunk itself wasn’t massive, but it was heavy enough that Finn immediately began complaining halfway through the walk.

"I don’t understand why we couldn’t sell something lighter first."

"Because steel makes money."

"I’d pay you to let me not carry this"

I had long been using bits of pocket money from my parents to fund everything, but this wouldn’t sustain my future endeavours.

Once we finally arrived in town, we immediately headed toward the blacksmith district.

The first forge belonged to a broad middle-aged blacksmith covered in soot and burns.

The moment we entered carrying the wrapped steel, he looked up from his work.

"...What do you kids want?"

I carefully unwrapped the metal chunk atop his counter.

"We’re selling steel."

The blacksmith snorted.

"Everyone sells steel."

Then his eyes landed on the metal properly.

His expression changed instantly.

Slowly, he stepped closer.

"...Where did you get this?"

"We made it," I answered calmly.

The blacksmith picked up the chunk and examined it carefully beneath the forge light.

He tapped it lightly against the counter.

Then frowned.

"This is too clean..."

His eyes narrowed suspiciously toward us.

"You steal this?"

Finn immediately looked offended.

"We worked ourselves half to death making that!"

The blacksmith ignored him entirely while continuing to inspect the steel.

Finally, he placed it back down carefully.

"...How much?"

Honestly, I had no idea.

I just guessed randomly.

"Eight silver."

Finn nearly choked beside me.

The blacksmith immediately barked out a laugh.

"Eight silver?!"

Too high.

Good to know.

"...Seven?" I tried.

"You trying to rob me, boy?"

Eventually, after several painful minutes of negotiation, we managed to sell the steel for four silver coins.

Which—

Was still an absurd amount of money for two thirteen-year-olds.

The moment we exited the forge, Finn stared down at the coins in disbelief.

"...People pay this much for metal?"

I smirked.

"People pay a lot for quality."

And apparently—

We had quality.

For the rest of the day, we continued visiting different merchants and forges throughout town.

Each reaction remained almost identical.

Confusion.

Suspicion.

Then interest.

Several blacksmiths even questioned where we acquired such refined steel.

Naturally—

I lied horribly.

"Family secret."

"Inherited technique."

"Ancient knowledge."

One blacksmith genuinely looked ready to kidnap us for answers. 𝒻𝑟ℯℯ𝑤𝑒𝑏𝑛𝘰𝓋𝑒𝓁.𝒸𝑜𝘮

By sunset, Finn and I finally returned toward the forest carrying a small pouch filled with silver coins.

Neither of us spoke for a while.

Then eventually—

Finn looked toward me.

"...Leon."

"Yeah?"

"I think we accidentally started a business."

A slow grin spread across my face.

"No."

I looked ahead toward the distant smoke rising from the bloomery near the shack.

"This," I corrected quietly, "is the beginning of an empire."

———-

The following morning, the clearing behind the shack was already alive with noise.

HSSSHH.

HSSSHH.

HSSSHH.

The waterwheel turned steadily within the river while the connected bellows continuously pumped air into the bloomery furnace.

Honestly—

Watching the machine operate still felt surreal.

Finn stumbled out of the shack rubbing his eyes before staring at the furnace already burning brightly.

"...You started without me?"

"We have work to do."

"It’s sunrise."

"And?"

Finn groaned loudly before grabbing a nearby bucket of charcoal.

Over the past few days, our steel production had become significantly smoother.

The first attempts were rough and inconsistent, but now that we understood the furnace better—and no longer had to manually operate the bellows—we could produce steel far more efficiently.

And more importantly—

We were making money.

A lot more money than either of us expected.

Several blacksmiths in town had already begun asking when we would return with another batch.

One even offered double the original price if the quality remained consistent.

Naturally—

That only made me more ambitious.

Because if different steel compositions produced different properties...

Then eventually—

I could create specialized materials.

Harder steel for weapons.

Flexible steel for springs.

Heat resistant steel for engines.

Every advancement would bring me closer to recreating the technology from my old world.

I tossed another shovel of charcoal into the furnace while speaking.

"Today we experiment."

Finn looked worried immediately.

"That word usually leads to explosions."

"Probably."

"...You say that way too casually."

I ignored him and unrolled several pages of notes across the worktable.

Most of the pages contained rough diagrams and equations from memory.

Carbon ratios.

Heat treatment estimates.

Material behavior.

Obviously, I couldn’t perfectly recreate modern metallurgy with medieval tools.

But I knew enough to massively surpass this world.

I pointed toward several marked sections in the notebook.

"Different steel properties come from carbon content."

Finn blinked.

"...What’s carbon?"

"The thing inside charcoal that makes metal better."

"That explanation somehow created more questions."

I grabbed several small containers filled with crushed charcoal powder.

"More carbon generally means harder steel," I explained while preparing the furnace. "But too much makes it brittle."

Finn crossed his arms.

"So we’re trying different amounts?"

"Exactly."

For the rest of the morning, we began creating multiple smaller batches of steel using slightly altered charcoal ratios.

Some batches remained softer and easier to shape.

Others became significantly harder after cooling.

One experimental batch cracked almost immediately during hammering.

Finn stared at the shattered metal pieces.

"...That seems bad."

"Too much carbon."

Another batch turned out unusually flexible compared to the others.

I bent the heated strip slightly before nodding in approval.

"...Interesting."

Finn looked over curiously.

"What’s special about that one?"

"If refined properly, steel like this could absorb repeated impacts without snapping."

"...You sound terrifying whenever you get excited."

Honestly?

Fair.

Hours passed as we continuously experimented.

The clearing gradually filled with failed samples and discarded slag while my notebook became increasingly crowded with observations and measurements.

Eventually, by late afternoon, I finally produced something promising.

A medium-carbon steel with relatively few impurities.

Strong.

Durable.

And most importantly—

Consistent.

I stared at the glowing metal quietly while ideas flooded my mind.

Gun barrels.

Mechanical gears.

Pressure systems.

Vehicle frames.

This steel alone wasn’t enough for those things yet.

But it was a foundation.

And foundations changed history.

Finn dropped onto a nearby chair completely exhausted.

"I never want to see steel again."

"You’ll see a lot more of it."

"That sounded threatening."

I smirked slightly before carefully placing the finished steel beside the others.

The forest clearing around us no longer resembled an abandoned ruin.

Smoke drifted upward from the active bloomery while tools, materials, and stacks of experimental metal filled the area surrounding the shack.

The constant turning of the waterwheel echoed softly nearby like the heartbeat of some growing machine.

Piece by piece—

Something extraordinary was being built here.

And nobody in the kingdom had the slightest idea.