Peak Between Two: Mushoku Tensei

The morning sun slipped through the windows of the Greyrat home, casting a golden glow on the wooden floor, warm beneath bare feet. The air was crisp with the scent of morning dew drifting in from outside. Birds chirped softly in the distance, creating a peaceful atmosphere—

Or at least, it should have been peaceful.

In reality…

"Hey, Norn! Stop that, you're pulling too hard!"

I let out a long sigh as I tried to pry my younger sister's tiny fingers from my hair. Norn Greyrat, now two years old, sat comfortably in my lap, her bright eyes sparkling mischievously as she tugged at my hair without a hint of guilt.

Beside her, Aisha Greyrat—my half-sister, also two years old—clung to my sleeve like a stubborn piece of glue, gripping my shirt with surprising strength.

Both of them were latched onto me with an attachment bordering on obsession. It was as if I weren't their older brother, but rather their favorite stuffed toy.

I sighed again.

"How did I—once a genius scientist in my previous life—end up being treated like a plaything by two toddlers?"

Norn giggled, completely ignoring my mild protest, while Aisha stared at me with her big, innocent eyes, waiting for my reaction.

The past two years had changed my life significantly.

Ever since Norn and Aisha were born, my peaceful existence in the Greyrat household had taken a drastic turn.

At first, I was just a child trying to live my second life quietly—playing with the village kids and occasionally dodging my father's brutal sword training. But once these two were born, I was suddenly given a new role: the responsible older brother.

Zenith and Lilia, despite loving their daughters dearly, had their limits. Paul? Don't even ask. He adored his children, sure, but… the man spent more time training or fooling around than actually helping with childcare.

And Rudeus? He was still in Roa, dealing with that infamous temperamental young lady of the Boreas family.

So, somehow… I became the one who looked after these two the most.

Maybe because I was calmer than Paul. Maybe because I was more reliable than Rudeus.

Or maybe…

They just liked me too much.

"Luciel!"

Norn suddenly called my name in a sweet, affectionate tone.

I turned to her. "What?"

She looked up at me with a bright smile. "Hug!"

I blinked a few times before sighing in surrender. I shifted Norn from my lap and lifted her into my arms, letting her snuggle against my shoulder.

Aisha, who had been quiet until now, immediately reacted. "Me too!"

She stretched out her tiny arms, her face scrunching up in a small pout, unwilling to lose to Norn.

I chuckled softly and pulled Aisha into the hug as well.

"Seriously, these two refuse to share their big brother, huh?"

Their warmth pressed against me, even on this already bright and sunny morning.

I could feel their tiny heartbeats—soft, steady, full of life. Their breaths tickled my neck as they clung to me, their small hands gripping my shirt tightly.

Sometimes, I wondered…

"Is this what happiness feels like?"

In my past life, I spent my days buried in books, numbers, and endless research. Loneliness was routine, and scientific challenges were the only thing that made me feel alive.

But now, my life was filled with crying babies, playful laughter, and the daily chaos that only an idiot father like Paul could bring.

And then there was Sylphiette, the elf girl who had become a constant presence around me.

She often helped take care of Norn and Aisha—though, more often than not, she simply played with them rather than actually looking after them. But I could tell that she had grown more confident since Rudeus left for Roa.

We trained magic together, and I pretended not to be too skilled, letting her believe that she was more advanced than me.

Even though we both knew who had really taught her magic.

Rudeus.

The thought made me exhale softly.

Master Roxy had also left after Rudeus reached a high enough level. I had hoped to train directly under her, but I was too cautious about drawing attention to myself.

And now, the only news from Rudeus came in the form of occasional letters from Roa, detailing his life as a tutor to a certain unruly noble girl.

Nothing significant had happened in my life.

Even though I enjoyed this peaceful existence, a part of me still craved… a challenge.

Damn…

I missed Ryusei.

As rigid and serious as he was, we used to do all sorts of ridiculous things together.

I smiled faintly at the memory, but a soft voice beside me pulled me back to reality.

"Luci?..."

Sylphiette gazed at me with her silver-green eyes, concern flickering in them.

"Why are you smiling by yourself?"

I shook my head slightly, masking it with a casual expression.

"It's nothing. Just remembering something."

Sylphiette blinked before smiling a little. "Then let's go back to training! Today, I want to improve my mana control!"

I nodded, and together we made our way to the training ground behind the Greyrat house.

The small yard behind the house was usually Paul's domain for sword training. But today, it would be our magic laboratory.

I stood in the center of the field, raising a hand.

"Alright, show me what you've got, Sylphie."

Sylphiette grinned excitedly and lifted her hands. The air around us shimmered slightly, and within moments, a sphere of water—about the size of a human head—floated effortlessly in midair.

She manipulated it smoothly, making it rotate before sending it forward.

Boom!

The water sphere burst upon impact with the ground, splashing across the field.

Sylphiette turned to me with expectant eyes. "Well?"

I nodded in approval. "Much more stable. You're no longer wasting extra mana to control it."

She beamed proudly. "I learned from the best!"

I merely offered a faint smile. If only she knew that I was far more skilled than she thought.

While Sylphiette continued experimenting with variations of her water magic, I stepped to the other side of the training ground and began testing something new.

Raising one hand, I channeled mana to my fingertips.

Magic in this world operated on elemental principles—water, fire, wind, earth, and so on. But what if I viewed it through the lens of science?

I closed my eyes, recalling the concept of matter transformation from my previous world.

Water magic… what if I could control it on a molecular level?

If I could separate hydrogen and oxygen from water, then I could create something far stronger than a mere water ball.

Holding out my palm, I shaped tiny droplets of water in midair.

Then, I attempted something I had never tried before.

I focused deeply, visualizing water in its most fundamental form—H₂O molecules.

I imagined pulling apart the hydrogen from the oxygen.

For a brief moment, the water in my hand vibrated.

But before I could stabilize it—

BOOM!

A small explosion erupted, scattering dirt and dust across the training ground!

I staggered back, glancing at my palm, which now felt slightly warm.

Sylphiette ran toward me in a panic. "Luci! What happened?! Are you okay?"

I turned to her, then glanced at the small scorch mark on the ground.

Slowly, my lips curled into a faint smile.

I had just proven something.

Matter transformation through magic was possible.

And if I could master this technique…

My magic would surpass anything this world had ever known.

After cleaning up the remnants of my little experiment, I sat beneath a tree, deep in thought.

If I could find a way to separate the elements within matter using magic, then the potential of magic itself would reach levels no one had ever imagined.

But this also meant… I had to be careful.

This discovery was too dangerous to fall into the wrong hands.

Just as I was contemplating my next steps, a sudden gust of wind rushed through the air.

I turned toward the village and saw several villagers running toward the Greyrat household.

My heartbeat quickened.

Something was happening.

I rose from my seat, staring at the sky, which was darkening as the sun slowly dipped below the horizon.

A bad feeling settled in my chest.

And for some reason…

I had the eerie sensation that my peaceful days were about to end.