Peak Between Two: Mushoku Tensei

-Luciel Greyrat-

"Ciel, stop daydreaming."

A soft yet firm voice pulled me back to reality.

I turned my head and saw Roxy Migurdia, my brother's magic tutor for the past two years, staring at me with her usual blank expression.

Roxy was a talented magician from the Migurd race, with short blue hair and a wizard's hat that she always wore. Her bright blue eyes seemed calm, but if you looked deeper, there was something there… something like hidden insecurity.

She was Rudeus' teacher.

I looked at her for a moment before letting out a small sigh. "Sorry, Master Roxy. I was just thinking."

She raised an eyebrow. "What could a three-year-old possibly be thinking so deeply about?"

I gave her a small smile. "That's a secret."

Roxy stared at me for a moment before shaking her head slightly. "Just like Rudeus, you always seem to be hiding something."

I simply smiled, neither confirming nor denying it.

Because she was right.

It had been nearly two years since Roxy arrived at our home to teach Rudeus magic.

From the very beginning, I knew that my brother was gifted. His talent for magic far surpassed that of children his age—even adults would be shocked by his abilities.

But more than that… I knew that my brother had a very colorful mind.

For some reason, whenever Roxy was around, his expression turned strange.

He was too enthusiastic, too focused on Roxy—or rather, on something else.

Sometimes, I caught him grinning a little too widely when looking at our tiny teacher.

Sometimes, I noticed his gaze drifting to places it shouldn't be.

And sometimes, when he thought no one was looking, I could hear his quiet whispers…

"Gahahaha… witch hats really are the best…"

…My brother is a genius in magic.

…But he's also a hardcore pervert.

As a former scientist, I could accept many things about this world… but my brother's habits were a bit hard to digest.

However, I continued observing.

I never showed my true talent in magic.

I never let anyone know that I was actually just as gifted as Rudeus—perhaps even more.

I simply observed.

Why?

Because I wanted to play it safe.

In my previous life, I was a scientist who shocked the world with groundbreaking astronomical research—discoveries that even made NASA tremble.

But in this world… I was nobody.

I didn't know the rules of this world.

I didn't know the dangers lurking beyond this village.

I didn't know the true extent of magic's power.

And as someone who always thinks before acting, I knew that I needed more information before making my move.

So, I stayed quiet.

I let my family believe I was just a normal child.

I let Rudeus take the spotlight, allowing Roxy to focus all her attention on him while I remained in the background.

I absorbed every bit of information I could gather.

Because one day… I would use it.

I shifted my gaze back to Roxy, who was still watching me.

She seemed curious—probably because I rarely spoke to her or showed much interest in magic.

"Luciel," she said softly, "why don't you ever try learning magic like your brother?"

I stared at her for a moment before giving a small smile. "I'm not really interested, Master Roxy."

That was a lie.

I was very interested.

But I didn't want anyone to know.

Roxy gave me a doubtful look. "I think… you're actually quite smart. You pay more attention to things than most children your age."

I simply gave her a thin smile.

She's sharp—just as I expected.

"I just like to observe," I said casually. "I feel more comfortable that way."

Roxy remained silent for a moment before nodding. "Alright… but if you ever change your mind, I'd be happy to teach you."

I blinked, a little surprised.

I didn't expect her to say something like that.

I thought she only saw me as an ordinary child—not someone worth teaching.

But her words made me reconsider.

I smiled slightly. "Thank you, Master Roxy. I'll remember that."

###

That night, after everyone had fallen asleep, I quietly slipped out of my room.

I carefully opened the window, making sure not to make any noise that could wake my family. The cool night breeze brushed against my skin, carrying the scent of damp earth and leaves from the fields near our home.

Without hesitation, I jumped from the second floor.

Of course, I wasn't foolish enough to jump without preparation.

Using water magic, I created a spiral-shaped cushion that softened my landing, making it feel as if I had jumped onto a bouncy surface of water.

The moment my feet touched the ground, I immediately made my way to my secret training ground.

A Scientist's Approach to Magic

Hidden in a secluded corner of the village, surrounded by trees, there was a small clearing I had prepared.

This was where I trained in secret.

This was where I experimented with magic.

This was where I tried to understand this world through scientific reasoning.

After three years of experimentation, I had developed several key theories about magic in this world.

1. Magic is Derived from Mana as a Form of Energy

Mana in this world operates like a manipulatable energy source, similar to electricity or kinetic energy back on Earth.

However, unlike electricity, which requires wires, or water, which must obey gravity, mana can move freely according to the user's will.

This means that mana can be modified, reshaped, and optimized.

If humanity in my past life could develop nuclear reactors, lithium-ion batteries, and solar energy, then in this world, magic could be advanced even further.

I just needed to figure out how.

2. Incantations Are Merely a Medium, Not a Necessity

Most people in this world require incantations to cast spells.

But I had already proven that incantations were not mandatory.

As I suspected, incantations serve only as a mental aid, helping magicians visualize the final result of their spell.

If someone could fully comprehend the process, they could completely bypass incantations.

Rudeus already did it.

And so could I.

But this raised another question…

If incantations could be skipped, wouldn't that mean the very structure of magic itself could be rewritten?

If magic functioned like a computational algorithm, then theoretically, I should be able to recode it and create something entirely new.

And that was the goal of tonight's experiment.

Creating a New Element

Up until now, the four fundamental elements of magic in this world were:

✔ Water

✔ Fire

✔ Wind

✔ Earth

But based on my observations, I believed that this was merely a limitation of human thinking.

If magic truly operated based on understanding and mental conceptualization, then shouldn't I be able to create a new element simply by perceiving the world differently?

Tonight, I would put that theory to the test.

I closed my eyes and took a deep breath.

I started by activating the mana within my body, feeling it surge like electricity through a circuit.

Then, I activated water magic, forming a small droplet at my fingertip.

Now came the important part—elemental modification.

Experiment #1 – Ice Magic

If water was a fundamental element, then ice was merely another form of water.

On Earth, water freezes at temperatures below 0°C (32°F).

Therefore, if I could decrease the kinetic energy of water molecules using magic, I should be able to freeze the water without changing its elemental composition.

I envisioned the water in my hand losing energy, its molecules slowing down, gradually solidifying into crystalized formations.

Within seconds…

The droplet of water turned into a shard of ice.

"…It worked."

This wasn't just normal water magic.

This was pure ice magic.

Which meant… I had just created a new element through scientific understanding.

But I wasn't done yet.

Now for the more dangerous experiment.

Experiment #2 – Plasma Magic

If fire was a fundamental element, then plasma was a form of fire at an extreme temperature and ionization state.

On Earth, plasma existed in things like stars, lightning, and nuclear reactors.

If I could increase the temperature of a flame drastically, adding enough electrical energy, I could convert normal fire into pure plasma.

I raised my hand and conjured a small flame above my palm.

Then, I visualized the fire's temperature rising.

I imagined electrons separating from atoms, creating an electric field powerful enough to generate ionized gas.

I pushed more mana into the process…

And suddenly—

The fire changed.

Its color shifted from red to a deep violet-blue, the flames vibrating rapidly. A faint humming noise filled the air, similar to the static charge of electricity.

I had done it.

This was plasma magic.

I stared at the glowing, unstable sphere of plasma floating above my palm.

Unlike ordinary fire, this energy pulsed, emitting a soft, crackling hiss like an electric current. The surrounding air felt scorching, yet the flames themselves didn't burn the way normal fire did.

I had successfully created something new.

However—

"Ah…"

Shit.

I couldn't control it!

I felt my mana draining at an alarming rate. I had never used a spell that consumed this much energy before. This plasma… was too powerful.

Without hesitation, I swung my arm and hurled the plasma sphere into the sky.

SWOOSH!

A streak of blinding blue light shot upward, piercing through the night sky like a laser beam, illuminating the entire village for a brief second.

I gasped for breath, collapsing to one knee as sweat dripped from my forehead.

"Shit…" I muttered, trying to stabilize my breathing.

I had succeeded in creating a new element, but at the cost of insane mana consumption.

If I couldn't figure out a way to optimize mana usage, then plasma magic would be useless in actual combat.

I needed to refine my technique.

I was deep in thought, running calculations in my head, when—

"Luciel?"

A voice called out behind me.

My blood ran cold.

NO. WAY.

I whipped around in panic.

Standing under the moonlight, her short blue hair illuminated by the faint glow of the remaining plasma residue, was a small figure wearing a pointed wizard's hat.

Her normally calm eyes were now wide with shock.

Roxy Migurdia.

She had seen everything.

"Hah—!?"