The ninja from "Hidden Construction Company" worked faster than most ANBU.
He checked the contract, confirmed my identity, handed over the goods, and left.
No extra questions.
No curious glances.
No "so what are you building, mysterious sir?"
Deliver workers, get paid, disappear.
Professional.
"I have to admit, sensei's supplier network is very competent," I raised an eyebrow, looking down at the group I'd just inherited.
Fifty laborers.
All adult men, all sturdy, arms and backs knotted with muscle.
And all with the same thing in their eyes—
that flat, empty look you only see on people who've long since realized they're no longer treated as human.
Perfect "expendables."
I picked a location about two kilometers away from Orochimaru's own lab—within support distance, but not so close that a single unlucky explosion would take us both out.
Rock, hills, and a neat little mountain.
"I'll hollow the mountain out and build inside," I decided.
Orochimaru's "gift package" even included a bonus sealing scroll full of tools: picks, drills, carts, reinforcing frames. Everything a villainous underground lab could ever need.
"My original doesn't want to try some 'gentle' method? You know—buy their hearts, earn loyalty?" one of my shadow clones asked beside me, sounding amused.
I gave him a deadpan look.
"Please. You and I both know how that would go. If I tell them 'you're free now,' they'll do exactly one thing—run. Very fast. Very far."
We were literally the same person; I knew exactly how I would react if I'd been trafficked here as disposable manpower.
In my previous life, people loved to say: Give someone kindness and they'll follow you forever.
Yeah. No.
Try testing that in the real world and you'll learn very quickly:
human nature does not pass stress tests.
I had no intention of "testing" anyone.
They were tools. Tools didn't leave bases, because tools could leak locations. And if this base got exposed because I got sentimental?
My own future would be on the chopping block.
"Alright, I'll leave monitoring and supervision to you two," I told another pair of clones. "Keep them working, don't let anyone slip away, and make sure they follow the layout plans."
The clones nodded. The original me turned back toward Orochimaru's lab.
I had more important problems to solve than labor management.
First priority: chakra storage devices for the upgraded thermobaric project.
The more chakra they could safely hold, the stronger the bomb could become.
Simple in theory. Annoying in reality.
"If I get this working, I'll have to name it properly…" I muttered, heating the metal and sketching seal patterns on a nearby board. "Fire–Wind–Lightning Thermobaric Bomb… ugh. Sounds like a child's move in a card game."
Way too tacky.
"Fine. Let's go with Thermobaric Bomb – Type II."
Clean, simple, scientific.
Name: done. Now all that was left… was to somehow make it real.
I started with chakra-conductive metal as the container. In theory, it should've been perfect.
In practice?
The moment I tried to infuse sage chakra into the metal, the entire container blew itself to pieces.
Not even a warning delay.
One instant: stable.
Next instant: boom.
Good thing the first test used wind-natured sage chakra, and I'd already prepped layered defenses. Otherwise, I'd be repainting the lab again—with my own organs.
"One problem isn't even solved and the next one's already knocking on the door…" I exhaled, flipping my notebook open and jotting down observations.
Honestly, I wasn't even surprised.
Research is just like that.
In my previous life too, every experiment was like opening a loot box of new problems. You'd solve one, three more would pop up from behind like they'd paid for a family ticket.
And this world's "science"… was a Frankenstein mess.
Some parts were way ahead of where they should be.
Other parts were stuck in medieval mud.
No wonder everything broke in such weird ways.
Back on Earth, I could've solved this with one simple move:
"Open a project tender. Specify the performance and safety requirements. Let ten different specialist labs burn their budgets fixing my problem."
Here?
There was no such thing as outsourcing science.
If I didn't build it myself, it simply didn't exist.
I rubbed my temples.
"If only sensei were here…"
The irony wasn't lost on me.
I'd basically become a hybrid: bio-researcher + weapons designer + part-time engineer.
But materials science?
Nope.
That wasn't my field—neither in my past life nor here.
Every discipline has its own specialists.
I wasn't some omniscient golden child who knew everything from genetics to metallurgy.
"Should've majored in materials back then," I muttered. "Biology was a mistake. That major is suffering. Dogs shouldn't study it."
Complaining felt good.
Didn't change the fact that the work still needed to be done.
So I did what any halfway responsible ex-researcher would do:
When you're not an expert?
Stop guessing.
Ask the people who are.
That lesson had been branded into me pretty early:
in junior high, when I nearly electrocuted myself trying to "experiment" with live wires based on half-remembered physics.
Since then: electricity was something I respected from a distance unless an actual professional was involved.
So.
Who knew the most about metals in this world?
Not academics.
Not ninja.
Smiths.
Weapon smiths, armor smiths, tool craftsmen—
the people tasked with forging blades that could endure chakra, heat, impacts, and time.
The problem: I couldn't stroll into a village and knock on a respectable blacksmith's door.
So that left me with the other option.
The one place where you could buy anything, from defective kunai to missing-nin.
The black market.
A week or so later, I stepped through the familiar gate into that filthy underground bazaar.
And immediately had to dodge a flying sandal.
"YOU BASTARD! I'M FORTY-FIVE ALREADY AND YOU STILL COME AFTER ME?!"
A furious woman hurled her shoe with such murderous intent it whistled through the air.
"YOU OLD PERVERT! I BATHE FIVE DAYS A WEEK, YOU SPEND ALL SEVEN OUTSIDE!"
Another woman, face flushed with anger and humiliation, flicked an explosive tag like a playing card.
It missed its real target.
It nearly hit me.
The resulting explosion lit up the alley in a burst of flame and smoke, dramatically framing the fleeing figure at the center of it all.
White hair. Red cloak. Loud laugh.
Jiraiya.
One of the legendary Sannin of Konoha.
Currently: being chased around the black market by a mob of enraged middle-aged women.
From the look on his face, though, he wasn't terrified.
He was… actually enjoying himself.
Of course he was.
"Ah…"
I quietly stepped to the side, letting the chaos pass in front of me.
No wonder Tsunade always wanted to punch him.
This man wasn't just a pervert—he was a professional pervert.
"Hmm?" Jiraiya's eyes swept across the street and brushed past me.
I gave him a casual little smile.
This time, I was using another face.
No chakra signature, no features that would link me to our last encounter.
Even if he stared straight at me, he shouldn't see anything but a random passerby in the wrong place at the wrong time.
Perfect.
Let the old man collect more "material."
I had my own project to push forward.
Note: If you're interested, you can read up to chapter 99+ at patreon.com/nakai01. Don't forget to give a power stone for many bonus chapters.