"Lord Rihan von Hayes. It's already been three months since you were parachuted into our department, hasn't it?"
The voice of Varman, director of the Second Research Institute at the Imperial Strategic Magic Headquarters, was cold.
Beyond the ornate, gold-leafed office desk.
Judging by the look in his eyes, he had already stamped my notice of dismissal.
I swallowed dryly and instinctively hunched my shoulders.
'Hss, this familiar pressure.'
My previous life on Earth flashed before my eyes like a revolving lantern.
Exactly one week before submitting to an international conference.
My advisor had worn just that expression while reviewing my paper, soaked as it was in all-nighters, hadn't he?
On Earth, I had been a graduate student majoring in physics, pulling all-nighters as routinely as eating meals at a particle accelerator research institute.
Just before I died of overwork, buried under papers.
I opened my eyes to find myself possessing the body of this world's incompetent noble son, "Rihan von Hayes."
The second son of the Viscount Hayes family.
My older brother, who was supposed to lead the family, was called a genius and was rising rapidly in the world.
But I, the second son, had mana sensitivity only on the level of an ordinary person, and was called the disgrace of the family.
In the end, the viscount had half given up on me and, after bribing the director, shoved me into a low-level administrative position here at the Imperial Strategic Magic Headquarters.
At first, I wondered what sort of nonsense this was.
But now, I was in the process of calmly accepting it.
In truth, the most important thing to me right now lay elsewhere.
This place I had entered through family connections.
The Imperial Strategic Magic Headquarters was, without exaggeration, a god-tier workplace.
A four-day workweek.
Guaranteed personal time.
And most decisively……….
'Cream soup with truffle oil and freshly baked rye bread for Tuesday lunch!'
The cafeteria food was insanely delicious.
Leaving this fantastic welfare benefit of my own accord was not something an intelligent member of humanity should do.
I had to cling on somehow.
My goal was to live thin and long, sucking the sweet nectar of this empire's capital.
"Yes, Director. Has it already been that long?"
I put on the kindest smile I could manage.
"Time truly flies like an arrow. Haha. Cruelly so."
"Are you laughing?"
Varman's brow narrowed.
"You can barely sense a rat's tail worth of mana. Rumors are rampant that you, unable to cast even a scrap of magic in this holy land of magicians, are doing nothing but wasting your salary. My patience has run dry as well. My friendship with the viscount ends here."
It was a painful thing to hear, but also perfectly accurate.
This body had mana sensitivity on the level of an ordinary person, after all.
If I were the protagonist of an ordinary possession story, I would shout for a status window here and obtain some fortuitous encounter.
But this place was brutally realistic.
There was no way such a thing existed.
Director Varman irritably threw a heavy bundle of documents at me.
"This is the last chance I am giving you. The chronic mana backflow phenomenon in the magic circle for the 4th-class spell 'Flame Storm.' Solve it. If you cannot, pack your things and leave tomorrow. Noble family face or not, I can no longer tolerate a waste of the national treasury."
"I can't even use 2nd-class magic, let alone 4th-class……?"
"Is that supposed to be something to brag about? I'm not telling you to cast it yourself. I'm telling you to reinforce the theoretical design as a magical engineer!"
Mm, it certainly wasn't something to brag about.
Leaving Director Varman's cold treatment behind, I slowly picked up the blueprint he had hurled down.
For now, should I at least take a look?
You never knew.
Maybe I had some amazing talent.
'Ahem, let's see.'
The blueprint was covered in incomparably complex geometric patterns, tangled together in disorder.
An ordinary person would have complained of eye pain within three seconds, but to my eyes, it looked different.
Strange.
For some reason, it felt familiar.
Like the messy schematics I used to see during thesis advising sessions, maybe?
'Hmm, wait a second. If mana is an aggregate of energy flowing along channels…….'
I wiped away the magical perspective entirely and reinterpreted the blueprint solely from the perspective of physics.
'………This is just a fluid dynamics problem, isn't it?'
Fortunately, even in a tiger's den, there seemed to be a way out.
****
After returning to my seat in a corner of the research institute, I stared holes into the blueprint.
In air mixed with the smell of ink and old parchment, I twirled my quill.
It was a habit from my previous life whenever I solved complicated equations.
'The people of this world revere mana as some intangible phenomenon, calling it a blessing of the gods or the resonance of the soul, but….'
The way I saw it, mana was simply a kind of energy fluid with a specific density and viscosity.
A fluid. In other words, a substance with flow, like a liquid or gas.
"The channels bend at 90 degrees, so of course a vortex would form."
It was the basics of fluid dynamics.
When flow bends sharply, a bottleneck occurs and pressure spikes.
It was only natural for the magic circle to explode.
I picked up my quill and began drawing lines over the blueprint.
I might not know grandiose magic theory, but I did know how to create efficient flow.
It was what I had done every day, so how could I not?
The physics knowledge in my head remained intact even after the world changed.
'Apply Bernoulli's principle here to control the flow velocity, and consider the Reynolds number here to turn turbulence into laminar flow. Add some boundary layer control to reduce wall friction resistance…….'
I smoothly adjusted the curvature of the magic circle.
In the sections where mana caused bottlenecks, I opened auxiliary channels to disperse the pressure.
I added minimal resistance, and even a heat dissipation structure to vent the heat generated when energy condensed.
I skimmed over the roughly reinforced blueprint.
'Urgh. It's a little lacking…….'
Honestly, if I put my mind to it, I could increase the efficiency here by another 500%.
But I was a professional salary thief.
If I did too well, work would pile up.
How did I know work would pile up?
I hadn't wanted to know either.
Enough digression.
"If I do this, it won't explode. Just enough not to get fired, exactly one person's worth of fixing."
I picked up the blueprint and rose from my seat.
With light steps, I headed for the testing ground.
*****
At the testing ground, Director Varman stood at the head of a group of renowned senior researchers, all gathered with their arms crossed.
Their gazes toward me were full of undisguisable contempt and sadistic curiosity.
"Let's see, Lord Rihan. Is this what you call your solution?"
Director Varman pushed up the magnifying glass perched on the tip of his nose and scanned the blueprint.
A moment later, his brow twisted beautifully.
"……What is this? Why have you twisted the mana channels into such winding shapes?"
Varman's voice carried irritation beyond mere disappointment.
"You don't even have the basics of orthodox magical geometry. This doesn't look like a magic circle, but the scribbles of a child who knows nothing of fundamentals. Is this how the Hayes family teaches theoretical magic?"
A researcher beside him chimed in while suppressing a sneer.
"Director, why not simply give up? It seems you expected too much from the second son."
'Mm. How should I explain this?'
I secured fluid dynamic stability by considering Bernoulli's principle and the Reynolds number?
And in the process, I used approximations of the Navier-Stokes equations?
'Goodness, not a chance. If I said that, they'd treat me as a heretic or call me insane.'
After a brief moment of thought, I opened my mouth.
Making myself look as simple-minded as possible.
"Well…… Director. This is a sort of matter of feeling."
"Feeling? Are you playing a prank in the empire's finest research institute?"
"If the path bends too stiffly when mana passes through the channels, wouldn't the mana get angry too? So I rounded the road a bit so it could flow comfortably, as if taking a stroll."
Director Varman let out a hollow laugh, as if he no longer even had the energy to get angry.
"Feeling? Mana gets angry? Hah, honestly…… In all my years, I have never heard such refreshingly novel nonsense!"
As if giving up, he pointed at the test target.
"Fine. Let us see what results your pleasant-feeling magic produces. Activate it at once. If even the slightest backflow appears, know that you will pack your things and leave immediately."
The trainee researcher glanced at me once with a pathetic look, then injected mana into the magic circle.
*****
Ordinarily, the 4th-class spell Flame Storm produced tremendous vibration and roaring just before activation.
That was because uncontrolled mana collided and flowed backward inside the magic circle, screaming as it did.
It was normal for an unpleasant, precarious roar to resound, like a pressure cooker just before it exploded.
But something was strange.
Whoooooosh—.
"………?"
There was only the sound of air escaping.
The mana flowed smoothly into the magic circle without resistance.
There was not even a flicker of light from any backflow phenomenon.
"Is this…… mana being injected? Why is it so quiet?"
Just as a senior researcher looked over the mana measuring device in puzzlement.
Kwaaaang—!!!
A dazzling flash filled the testing ground.
It was different from an ordinary Flame Storm.
A pillar of ultra-high-temperature flame, like a plasma cutter, with thermal energy condensed into a single point and accelerated, pierced straight through the wall.
"………?"
Silence flowed through the testing ground.
The target, a 30-centimeter-thick mana-resistant steel plate, had evaporated without a trace.
Director Varman stood with his mouth wide open.
Unaware that the magnifying glass perched on his nose had fallen to the floor, he stared at the wall that had been pierced through.
Toward their stupefied faces, I asked indifferently.
"……It works, doesn't it?"