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Mushoku Tensei: Oldeus Starts Over

Summary:

Oldeus lost everything.

After decades of regret, Rudeus Greyrat develops Time Magic in one final attempt to change the past. But instead of meeting his younger self, his soul awakens inside his own childhood body.

Armed with a lifetime of memories and roughly ten years before the Teleportation Incident, Rudeus gets one final chance to protect everyone he failed to save.

The problem?

The more he changes, the less useful his knowledge of the future becomes.

Notes:

(See the end of the work for notes.)

Chapter 1: Prologue “Decades After That”

Chapter Text

“Even after suffering defeat, life must go on.”

Defeat isn't shame. Compliance is significant.

Author: Rudeus Greyrat

...

Before me was a room dominated by a massive magic circle.

The walls were haphazardly covered with sheets of paper bearing rough sketches, and the floor was just as cluttered.

I stood before the magic circle and slowly closed my eyes.

Just how had I ended up all alone like this?

I had been happy once.

I had married two women and lived a blissful newlywed life with my family in a vast mansion. From the bottom of my heart, I wished those days could last forever.

My children would run around the house, filling it with noise. Zenith and Lilia would watch them with contented smiles, while I sat nearby with my two wives, enjoying our life together.

It was a scene I had imagined countless times, and for a while, it seemed as though my life was actually heading in that direction.

Then, at some point, everything fell apart.

“Ru...dy...”

About fifty years ago, Roxy contracted an unknown disease. The tips of her toes began turning into purple crystals.

I immediately contacted Cliff and asked him to confirm the diagnosis with his Eye of Identification.

The disease was called Petrification Syndrome. It was a terminal illness that could only be completely cured with a God-tier Detoxification spell.

By the time I returned with a scroll containing a God-tier Detoxification spell, everyone looked grim. Half of Roxy’s body had already turned to crystal.

She was dead.

The spell had come too late.

“Rudy... I love you...”

Not long after Roxy died, Sylphie tried to seduce me.

Looking back now, something about her behavior at the time was clearly wrong. She said that holding her might help me forget about Roxy. She wouldn’t let it go until I finally lost my temper with her.

How could I possibly hold her after hearing something so thoughtless?

But that wasn’t the only reason.

If I had embraced Sylphie then, I knew I would have treated her roughly.

I would have used her as a substitute for Roxy, as an outlet for all the emotions bottled up inside me.

I thought... that would have been wrong.

By the time I realized something was amiss, she had already left without saying goodbye.

When I later tried to find out what had happened to her, I learned that she had gone to the Asura Kingdom with Ariel and her group.

Overcome by a terrible premonition, I rushed to the Asura Kingdom like a madman.

But by the time I arrived, it was already over.

Ariel had lost the political struggle, and everyone associated with her had been executed and put on public display.

Sylphie included.

Sylphie’s corpse was missing an arm, and deep slash wounds marred her face. People threw stones at the displayed bodies, treating Sylphie as a criminal who had disturbed the peace of the capital.

“Rudeus... run...”

About forty years ago, for certain reasons, I ended up fighting the Immortal Demon King Atofe.

My opponents were Atofe and every member of her personal guard.

I thought I had a chance of winning, but Moore interfered. I had let my guard down completely. I knew perfectly well that Moore was an exceptionally capable magician, yet I had focused all my attention on Atofe.

When they finally cornered me, Eris suddenly leaped into the battle.

She protected me.

And died because of it.

Her body was torn in two, the pieces falling at my feet.

My memories of the thirty years that followed are hazy.

All I can really remember is an almost obsessive pursuit of strength.

Gravity magic. Electricity magic. Sound magic. I even pushed my voiceless healing magic to the Saint-tier level.

I became stronger.

Far, far stronger.

I could even boast that there was no mage alive in the world more powerful than me.

But what did that strength cost me?

Everyone I loved, my entire family, was gone.

I was the only one left.

There was only one reason I had kept myself alive for so long.

Even now, I could still hear that bastard’s voice from the moment he finally revealed everything to me.

I could still feel his hand on my shoulder after he said, “You’ve worked hard.”

That shrill laughter...

Damn it!

Bastard!

I would take revenge on the mastermind responsible for every one of those tragedies.

I would tear him to pieces.

“HITOGAMIIIIIIII!”

A roar of fury erupted from my aged body. In that instant, purple lightning scattered in every direction, illuminating the room as brightly as day.

I knew perfectly well that no matter how furious I became, there would be no answer.

Even so, I couldn’t suppress my murderous rage.

Sylphie, Roxy, Eris, Norn, Aisha, Zenith...

Every one of them had been harmed, directly or indirectly, by Hitogami.

Words could no longer describe how much I hated him.

But I couldn’t find him.

He still appeared in my dreams from time to time, mocking me in my wretched state, yet no matter what I did, I could never discover where he was.

I once tried to find the Dragon God Orsted, whose goal was also to kill Hitogami, hoping that I could join forces with him. But after Nanahoshi committed suicide, searching for him became extraordinarily difficult. Even after all these years, I had never managed to cross paths with him.

With every other method exhausted, I had only one path left.

I turned toward the magic circle.

This was the culmination of decades of research.

The Time-Travel Magic Circle.

Long ago, I had reached a conclusion.

Magic was all-powerful.

Once you understood how it worked, there was nothing it couldn’t do.

Even returning to the past.

Once I realized this was the only possible way to defeat Hitogami, I spent roughly twelve years researching time magic.

I ran my hand over a book with a tattered cover. Written across it in Japanese, a language only I could read, was the word “Diary.”

I was certain I remembered correctly.

I had started writing this diary shortly before following Hitogami’s instructions and opening the basement door.

The principle behind this magic circle was to trace an object back through time to its point of origin.

In other words, the diary and I would return to the moment when I had first been about to write it.

There, I would meet the Rudeus of the past.

I would tell him about Hitogami’s plot and the despair that awaited him in this future.

I would make sure he did everything in his power to avoid this outcome.

Even if it meant I died.

The Grandfather Paradox?

Who cared?

If I could change a future this hopeless, I would gladly walk through fire and water.

I placed the diary in the center of the magic circle, then slowly moved to another position within it and began pouring in all the mana I could muster.

The magic circle exerted a tremendous pull, devouring every bit of mana I poured into it.

But I couldn’t stop.

The Time-Travel Magic Circle required an enormous amount of mana. In the entire world, perhaps only I or the former Demon God Laplace possessed enough to activate it.

As I continued pouring mana into the circle, the pattern beneath my feet gradually began to glow blue.

“Ooooooooooh!”

A low roar forced its way from my throat.

The blue light grew brighter and brighter.

Then, at a certain point, it erupted into a brilliant radiance.

My consciousness vanished.

Just before everything went dark, I thought I heard something shatter.

...

When I regained consciousness, my first thought was how bright it was.

Strange.

Shouldn’t it be the middle of the night at the Greyrat residence?

Where had I been transported?

My vision was filled with light, forcing me to squint in discomfort.

As my eyes gradually adjusted, I realized that a young blonde woman was looking down at me.

Beside her was a brown-haired man, also quite young, wearing a stiff smile.

The man looked strong, with an astonishingly muscular build and a rather headstrong air about him.

His hair was a rich, natural shade of brown.

But none of that mattered.

What mattered was that I knew these two faces all too well.

“...!”

I tried to roll over and sit up, but for some reason, my limbs had no strength.

Then I raised my hands in front of my face and realized something.

They were tiny.

They were the hands of a baby.

The woman looked at me and smiled softly before turning to the man beside her.

“That’s wonderful, dear. He seems to be a very lively child.”

“That’s a relief. For a moment, I thought something might be wrong... Come to think of it, though, this child isn’t crying at all.”

The man answered, visibly relaxing.

The two of them spoke for a little while longer before looking down at me together, their expressions filled with affection.

I see.

So this was a dream.

What a gentle dream.

As I looked at their warm, smiling faces, I could no longer hold back my tears.

“Ah... waaah...”

In Armored Dragon Year 407, the clear cry of a newborn baby echoed through the Greyrat residence.

The child was the firstborn son of the Greyrat family.

His parents named him Rudeus Greyrat.