Chapter 1: The Mentor System Awakens
My name is Allen black.When I died, I thought that would be the end. No more pain, no more struggle. Just… nothingness.
But no. That would've been too easy.
Some omnipotent cosmic sadist decided that death was far too boring for me. So, instead of letting me rest in peace, they tossed me into another world.
And not just any world.
No, they dropped me into the damn Nasuverse—a reality where Counter Guardians exist, where humans and mages are often more monstrous than the actual monsters. A world where f****** vampires don't just suck blood—they manipulate reality.
Yeah, I was pissed.
So here I was, stewing in frustration, trying to figure out how to survive long enough not to get killed by some Dead Apostle or get erased by the Counter Force.
Ding.
A sound echoed around me.
I turned around, and there it was—a glowing blue screen, floating in the air. It read:
[System Activating...]
I blinked. A system? Just like in those Isekai stories? I couldn't help but grin as my mind started racing a million miles per hour. If I had a system, then I had a chance. A real chance to dominate this world.
I watched with anticipation as the system finished booting up.
Then, my smile froze.
[Great Mentor System Activated]
[Warning: You can only have ONE student. No exceptions.]
What the actual hell?
If I were in the Age of Gods, this wouldn't be a problem—I'd have a pool of divine prodigies to choose from. But no. I was in the modern era, where mages were psychotic and extremely territorial. Basically, the type of people I was actively trying to avoid.
I sighed, rubbing my temples. "There has to be a workaround..."
Then, it hit me.
The year is 1994.
That means the Fourth Holy Grail War just ended. And that means—he is still young and untrained.
My grin returned. Avenger's vengeance, indeed.
There was only one person in this age with the potential to reach the Throne of Heroes—Emiya Shirou. The boy destined to become the idealistic, self-sacrificing hero who would one day become a Counter Guardian.
"System," I asked. "List your functions."
[System loading...]
[Functions Initialized.]
Power of a Mentor: You gain half the strength your student gains. The stronger your student becomes, the stronger you become.
Hidden From the World: You are shielded from detection by the Counter Force and Root. The world accepts you as part of its system.
World Navigator: A guidance system that ensures you make the right decisions, both to protect yourself and lead your student to greatness.
[Warning: You may only choose ONE student. This will not change. Choose wisely.]
I exhaled slowly. The system's warning was clear. If the world discovered I wasn't native to it, it would erase me instantly.
But now, at least I understood the rules of the game.
I opened the inventory tab.
…$50,000 in cash. That's it.
No weapons, no artifacts, no magic books. Just cold, hard currency.
Still, there was no time to complain. This wasn't about me becoming the strongest. My student had to reach the top—and I'd be dragged up with him. So the only thing left was to find him.
I was in Tokyo. Beautiful city, but not where I needed to be. It would take a day to get to Fuyuki.
Time to move.
I arrived in Fuyuki by plane. The city was quiet, the scars of the recent fire still fresh in the minds of its people.
I asked a few locals for directions near the site of the great fire. They looked at me with a mix of suspicion and pity—some probably assumed I was a relative of someone who died in the blaze.
I wandered aimlessly, searching for a clue, anything that would lead me to him.
Then I saw him.
A red-haired boy, no older than ten, running down the street with a grocery bag in hand.
My breath hitched.
His features were unmistakable—the messy red hair, the golden eyes, the faint frown of responsibility carved too early into his young face.
Shirou Emiya.
My heart skipped a beat. Excitement surged through me.
I followed him. "Hey, boy!"
He stopped and turned, looking at me with a polite yet cautious expression.
"Yes, sir? Did you call me?"
I expected him to be polite. What I didn't expect was his demeanor. The boy stood there not like a child, but like a machine programmed to react instantly if something went wrong.
He wasn't just human. Not anymore.
He was already becoming the weapon.
"Do you know someone named Emiya Kiritsugu?" I asked.
His eyes narrowed. He was studying me, trying to decide if I was a threat. But after a moment, he nodded.
"He's my father. If you want to meet him, come with me. I'm heading home."
I followed him in silence.
Everything about the boy—his gait, his focus, his awareness—spoke of discipline far beyond his years. He wasn't a child. He was a blade, forged too early and tempered by trauma.
I always knew Shirou Emiya was more weapon than man.
But seeing it firsthand?
He was far more dangerous than I ever imagined.
A weapon that could learn. Adapt. Evolve.
And eventually, become capable of killing anything—simply because he believed he had to.
Of course, he had two weaknesses: his abysmal mana reserves and his fragile physique. Those were the only shackles holding him back from becoming an unstoppable killing machine.
And it was now my job to break those shackles.
Because if I was to survive in this world…
…I needed to raise a hero.
As I followed Shirou through the quiet streets of Fuyuki, I mentally prepared myself for the next challenge—meeting Kiritsugu Emiya.
After all, this man was Shirou's guardian. And everything I knew about Kiritsugu told me one thing: he would sacrifice anyone—anyone—in an instant for the greater good.
Anyone but Shirou.
Shirou was his salvation. The one person he wouldn't trade, even for the world.
Which meant I had to tread carefully. I couldn't afford to provoke the Mage Killer.
I started running through possible approaches in my head. How could I convince him to let me mentor his son? What words would gain his trust without raising suspicion? Every scenario I considered ended in me either being ignored… or eliminated.
Lost in thought, I nearly missed the moment we arrived.
Shirou stopped in front of a modest Japanese-style home—the Emiya residence. The place looked peaceful, serene even, but I knew better than to judge by appearances. This house had seen fire, death, and silent suffering.
As Shirou stepped inside, he called out with youthful energy:
"Dad! Mom! I'm home! And Dad—there's a man who wants to meet you!"
Mom?
That word slammed into me like a truck.
My thoughts halted. My breath caught in my throat.
"Mom?"
That... wasn't supposed to happen.
The only timeline where Shirou might have a living mother is Fate/Kaleid—and even then, things are… different.
But in the main timeline? In the Nasuverse I know?
Shirou never had a mother. He knew nothing about the Moonlit World. He was just a kid saved by a dying man with a dream.
So naturally, I expected to see Irisviel, maybe even Kiritsugu himself. Perhaps one of the Einzbern maids if fate really wanted to play games with me.
But none of them came.
Instead, who stepped out to greet us nearly gave me a heart attack.
Standing in the hallway, casually wiping her hands with a kitchen towel, was Artoria Pendragon.
King Arthur. The Once and Future King. The Saber.
I froze. My eyes wide. My mind blank.
She shouldn't be here. She couldn't be here.
This wasn't the Holy Grail War. She wasn't supposed to exist in this time. Let alone… live here.
But the real shock came next.
Shirou walked up to her with a smile and held out the grocery bag. "Mom! Here are all the groceries!"
Mom.
He called Artoria Pendragon Mom.
I felt the blood drain from my face.
This wasn't just an alternate timeline.
This was a completely divergent worldline—one where Artoria survived the Fourth Holy Grail War… and stayed. Possibly even married Kiritsugu.
A timeline I had zero knowledge of.
Which meant all my information, all my assumptions, everything I thought I knew about the Nasuverse?
Useless.
I was flying blind now.
And in a world this dangerous, ignorance isn't just risky—
It's a death sentence.