[MF] Ch 19 ~ 21

Ch 19: Exterminating the Old Worm

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Let's roll back the clock—one minute before Kirei Kotomine sensed the magical tremor from the Matou estate.

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High above the compound, a thousand meters in the night sky, hovered a figure clad in gleaming, high-tech armor. Kaito had once again donned the guise of Iron Man Tokiomi Tohsaka, his next target clear.

Robbing the Matou household.

Yes, robbing it. Just like he had with the yakuza in Mifune City.

The difference this time was that the racket would be a lot bigger. There'd be no quiet surgical job like last time.

Clearly, the main reason was still money—funds for creating puppet avatars. But if it were only about money, there were far better targets than the Matous. Given the constraint of staying in character as Iron Man Tokiomi, any out-of-character behavior could cost him the card.

So the best option was something like the half-buried ruins scattered across India and elsewhere—sites still hiding unclaimed treasure. In Western terms, those were "ownerless" artifacts—perfect for a bit of American-style archaeology.

Kaito could have gone digging easily, and it would've suited Iron Man's character perfectly. After all, Tony Stark reborn as a magus? American archaeology was practically written into the résumé.

So why still here? Simple. The Matou estate held more than just assets. Here, Kaito could farm for fun points as well. Everyone else had already given him some. No reason to let the Matous off the hook.

He hadn't done it earlier only because other priorities had gotten in the way. Now was the perfect time to cross both items off his list.

Besides—beating up the Old Worm was practically a rite of passage for anyone crossing into the Fate world. For "Iron Man Tokiomi," whose hatred ran bone-deep, this was even more personal. After all, he was Sakura's father. Knowing what had happened to her in the Matou house, could any version of Tokiomi Stark not explode with rage?

This wasn't just Kaito's vendetta. The very character card was vibrating with satisfaction.

First things first—he sent J.A.R.V.I.S. and a swarm of nanobots down to scan the compound inside and out. Once he had the layout mapped, Kaito angled the suit downwards and dropped like a meteor.

As he approached the rooftop, his palm lit up. A blast of condensed energy ripped through the night and hammered the barrier protecting the mansion.

The supposedly sturdy enchantment shredded like burned paper, collapsing in an instant.

Then—KABOOM

The ceiling cracked, the storage above exploded in splinters, and a second thunderous crash announced Iron Man's iconic landing pose: one knee down, fist to the floor, blue optics glowing in the dark.

He'd chosen the study on the second floor for his entrance. The wooden flooring there shattered under impact, but Kaito stood steady, perfectly balanced.

The whole breach took mere seconds. Too fast for Zouken Matou, hunched over in the study, to process what had happened. His grotesque eyes bulged in disbelief, locked on the armored figure that had just crashed into his sanctum.

Five centuries of existence hadn't prepared him for this. The sudden failure of his wards, the absurd sight of a futuristic armored man—this was beyond anything Zouken's rotten brain could compute. His mental CPU froze.

Kaito straightened, faceplate gleaming. The twin blue optics fixed on Zouken with a focus that radiated lethal intent. In that cold light, the decrepit magus glimpsed his own death.

Yes, even through electronic eyes, he could feel it.

Zouken forced a crooked smile, trying to play the gracious host. "Hehehe… an unexpected guest. Perhaps we can—"

"Shut up. I don't feel like talking, and you're not worth listening to."

Kaito cut him off with the classic line. His hand rose—and fired.

A particle cannon burst to life, spitting a beam of destructive energy.

Normally, Iron Man enjoyed trash talk in battle. But when he was serious—when he meant to kill—he didn't waste a word. Straight to the point. No nonsense.

The blast looked like an ordinary blue repulsor shot, but this one carried something special. Kaito had edited the character card specifically: {after discovering the Matou family's secrets, Iron Man researched the anti-Zouken suit.}

The beam wasn't just energy—it carried a burning effect tuned precisely to Zouken's unique biology.

The Old Worm reacted instantly, unleashing a tide of insects to shield himself. But when the beam hit, the swarm ignited. Blue fire spread like a plague, consuming his familiars, then licking straight onto his body.

Zouken howled. This flame was different—it scorched not only flesh but the soul.

He panicked, dissolving his form into countless worms in a desperate bid to scatter. But the fire spread with him, as if each fragment of his body was fuel waiting to burn.

No—This wasn't "as if." It was fact.

Iron Man had designed it that way. By analyzing Zouken's cells, magic, and soul, he'd created an energy attack that used Zouken himself as fuel. The flames would hunt him, burn him, and never let go.

The infamous blue fire.

And it wasn't just for Zouken. The same research had led to broader applications—a magus-killer weapon. Against most magi, it would work just as well.

Sure, it wasn't exactly humane. But given what magi were like, Iron Man Tokiomi deciding to engineer an "anti-magus" arsenal felt pretty damn reasonable.

The "Anti-Magus Armor" had been part of the character card's setting. The upgrade to nanotech just folded the feature neatly into the current suit.

...

Zouken realized all too fast that he was being annihilated. He triggered a desperate explosion, detonating the already-burning worms to create a violent magical blast.

The study tore apart, shockwaves rippling out—the exact surge Kirei had sensed earlier.

Meanwhile, Kaito calmly swept the room. Even as debris rained down, he was looting every book, scroll, and shiny object into his system's inventory at lightning speed.

That was why he hadn't followed up with another blast immediately. With nanobots monitoring every inch of the estate, Zouken couldn't hide forever. Kaito had time to rob the place clean while the extermination process ran its course.

And of course, he made sure to squeeze out every possible fun point in the process.

It was worth a laugh, though. For all his notoriety, Zouken wasn't even rated a main player in the Fourth Grail War. The system only classified him as a supporting character. His total fun-point yield? A pathetic 387.

Barely better than Risei Kotomine.

What a useless old bug.

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Ch 20: The Matous

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After sweeping every valuable item from the study, Kaito didn't waste a second—he hunted the old worm while looting the rest of the mansion like a one-man demolition crew.

The Fun System's storage wasn't infinite, but it was massive—about half a football field wide and five meters tall inside. If it weren't for the fact he couldn't just store the entire Matou mansion outright, Kaito probably would've done exactly that.

The storage process itself was simple: just hold something and it'd vanish into the bag. He didn't even have to lift it; the touch alone was enough, meaning even huge objects could be instantly stored.

So right now, while Zouken Matou's magical explosions wrecked the area, Kaito's Iron Man suit blocked the blasts while he continued casually pocketing everything... yeah, everything.

Like the study's collection of books that might look like just ordinary tomes, but for a magus family that had survived for centuries—with its founder still wriggling around—they were priceless treasures in the magical world. Same for the safes and antique ornaments.

Selling them later wouldn't be Kaito's problem anyway. He'd just hand them off to Touko Aozaki. His job right now was simple—become a storm of plunder.

...

"Oh Zouken, my dear~ why are you struggling?"

At the moment, the old worm had literally turned into worms, scattering throughout the entire mansion.

After all his years of self-modification, Zouken Matou had long stopped being human. His "body" was just a hive of insects that could split and reform at will.

But that kind of structure needed a core, and indeed—one specific worm served as his true body.

In the Fate original, after finishing Sakura's transformation, Zouken hid his core inside her body. So killing him was notoriously difficult—he was one of the hardest beings to eliminate in both the Fourth and Fifth Wars, a true pest who refused to die.

Zouken made cockroaches look humane; at least they have the decency to die.

But no matter how sinister or grotesque his abilities were, against "Iron Man Tokiomi Tohsaka," the special persona Kaito had created, the old worm was facing his nemesis.

He couldn't handle Kaito's offense at all. Every time his worms tried to flee, miniature cannons materialized from thin air and shredded them instantly.

Those cannons were formed by Kaito's nanobots—microscopic drones that hovered invisibly in the air, ready to assemble into floating turrets whenever a target appeared.

It was, frankly, absurd. Not even Marvel movies featured tech like this—it was straight out of comic-book nonsense. But in Kaito's setup, "Iron Man" had merged technology with the world's magic system. The armor even incorporated the Volumen Hydrargyrum: Marrow of the Moon Spirit, created by the most unfortunate man of the Fourth War, Lord El-Melloi —Kenneth El-Melloi Archibald.

Using that high-tier magical framework, Kaito achieved wireless energy transfer and remote nanobot control.

Yeah, it was pure "turn off your brain logic." The kind of thing you justify after the fact with "it makes sense if you don't think about it."

But as always, as long as the system considered the setup internally consistent, the Fun System would make it real.

So right now, Kaito had completely sealed off the Matou residence. It didn't matter how Zouken tried to escape—even tunneling underground wouldn't save him.

Basic detection functions were standard, and with Iron Man scanning, Kaito had already mapped fifty meters beneath the mansion.

Zouken couldn't hide that deep anyway. At best, he could slither through the sewers.

Naturally, Kaito sealed those too. The old worm had nowhere left to go.

It didn't take long for Zouken to realize this. Fear and rage twisted inside him as he tried to counterattack—only to find he couldn't even get close.

The armor emitted infrasound waves inaudible to humans but devastating to Zouken's insect bodies. Any worm that got near simply burst apart.

A true hard counter.

For the first time in centuries, Zouken Matou felt genuine terror—deep, primal fear.

In all his long, twisted life, he had seen countless powerful beings, even the Magician of the Second Magic, Kischur Zelretch Schweinorg. They were all stronger than this "iron man," sure, but none of them had ever neutralized him so completely.

Now, the world offered no escape. Fighting was pointless. Running was useless.

Why? Why was this happening?

He couldn't comprehend it. What grudge did this armored figure have against him? Why go to such extreme lengths, cutting off every possible chance of survival?

Fear, confusion, and panic surged through his ancient, rotting heart.

"I have to live!"

"I must live!"

"I can't die here!"

The old worm shrieked and raged, his will to survive burning hotter than ever.

He couldn't accept this. He had lived for centuries, endured everything, and was finally close to eternal life through the Holy Grail—he wouldn't let it all end now.

He had abandoned family, past, and ideals. All that remained of Zouken Matou was a rotten, pathetic will to keep living.

So he scuttled toward another room on the second floor.

Inside were two people—his son, Byakuya Matou, and his grandson, Shinji Matou.

Zouken planned to use one of them as a new vessel.

Even if the chance was slim, he'd take it. Even if both died in the process, it didn't matter.

Because the only thing that mattered was his own survival.

"Hehehe… this old man must survive, no matter what!"

That was Zouken Matou's obsession.

That single, festering willpower churned within him, and the "Fun Points" generated from his extreme emotions skyrocketed—he was moments away from maxing out Kaito's current earning capacity.

...

Meanwhile, at the far end of the second-floor hallway, Byakuya and Shinji huddled together in the bedroom, trembling.

When Kaito had broken into the mansion and the explosions began, they'd both panicked instantly.

Byakuya had rushed straight into his son's room and dragged him into a corner, shaking in fear.

His life had been a tragedy from the start. As Zouken's son, he had been treated as nothing more than a spare body since birth.

And not long after Shinji was born, Zouken had fed Byakuya's beloved wife to the worms right before his eyes.

That day, something inside Byakuya shattered. He couldn't resist. He couldn't even try. So he gave up completely, drowning himself in alcohol and despair—his pathetic form of rebellion.

"If my body's just a spare," he'd thought, "then I'll destroy it myself."

A sad, foolish kind of defiance.

But tonight, he was sober. And when the mansion shook, the first thing this broken man did was rush to protect his terrified son.

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Ch 21: I'm... Iron Man

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"Dad, I... I don't wanna die..."

Shinji Matou was terrified. Terrified beyond reason.

At only five years old, he didn't understand what was happening. All he knew was that strange sounds were echoing outside, the ground trembled with every blast, and sometimes, through the noise, he could hear distant, blood-curdling screams.

If he listened closely… it almost sounded like his grandfather screaming.

The thought made Shinji's body tremble. His grandfather—that man—was his living nightmare. The most terrifying devil in his life.

He could never forget that day... a year ago, when his grandfather took him into the basement and showed him what was down there: countless insects crawling over each other in the dark.

That day, the chittering sounds, the stench, and the twisted grin on his grandfather's face etched themselves into his mind. The memory never left him.

And now, tonight, that nightmare had come back to life. The sudden attack had completely shattered the little boy's fragile sense of safety. Even when his father, Byakuya Matou, burst into the room to protect him, Shinji couldn't feel safe—because he knew the truth.

In front of that monster, even his father was nothing more than a puppet.

Then, without warning, a loud buzzing filled the air. Countless worms poured into the room, swarming together until they fused into the upper half of a human body.

Zouken Matou had arrived.

The sight was so horrifying that both father and son froze pale-faced in terror. They couldn't even close their eyes or scream; their bodies no longer obeyed them. Only their thoughts remained their own.

Zouken had taken control. Through their shared bloodline, he could directly dominate his descendants—and he was doing exactly that to make his next move easier.

"Your existence…" Zouken hissed, his face twisted and grotesque, "is to let this old man live on!"

BOOM!

Before he could finish, the wall beside them exploded. A figure in red and gold armor blasted through the debris, raised an arm, and unleashed a blinding shot straight at Zouken.

The old worm barely had time to scream before his distorted body was vaporized into ash.

And just like that, the superhero—Iron Man—made his grand entrance.

The sudden explosion of light and sound left both father and son staring in disbelief, eyes wide, mouths hanging open. When Zouken died, their bodies were released from his control, but their minds still hadn't caught up. They just stood there, stunned, staring at the gleaming red armor that looked both alien and beautiful.

The armored man didn't speak. He raised his hand, fired a shot that blew the window open, and cold night air rushed into the room.

Then, before either of them could react, Iron Man grabbed them both—one in each hand—and flew out through the shattered wall.

Moments later, they landed safely on the grass outside.

Setting them down gently, the armored man spoke in a calm, almost casual tone. "Looks like you two got lucky. I know, that wasn't a pleasant experience… you'll probably have nightmares for a while."

He paused for a moment, then added with a hint of warmth, "But after tonight, those nightmares should end. From now on, you're free. Live however you want."

He turned slightly, his voice shifting back to business. "Now, if you'll excuse me, I've still got some bugs to clean up."

He was about to take off when a small, trembling voice called out behind him.

"Um… excuse me! Who are you? Are you… a hero? Like Kamen Rider? Or the Super Sentai?"

Kaito stopped mid-step. Then he turned around.

Facing the timid boy whose eyes shimmered with hope, the expressionless mask of the armor seemed almost to smile.

"Yes," he said. "I'm a superhero. Remember this, kid. I'm... Iron Man."

With that, he turned back toward the mansion and shot into the air, vanishing through the broken wall.

For a few seconds, silence hung in the night. Then Byakuya finally snapped out of his daze, dropping to his knees and hugging his son tightly.

But little Shinji wasn't scared anymore. His face was flushed with excitement, and his wide eyes gleamed with pure admiration.

That moment was burned into his heart.

"Thank you… Mister Iron Man."

At that exact moment, on Kaito's end, a new achievement notification popped up.

[Achievement Unlocked: "Shinji Who Saw the Hero's Light: I'm Iron Man"]

[Reward: +500 Fun Points]

The accompanying image showed young Shinji's glowing eyes reflecting Iron Man's figure—a boy filled with wonder, destined to walk a very different path than the one fate originally planned.

For this Shinji Matou, superheroes weren't just fiction anymore. They were real. One had appeared before him, saved him and his father, and destroyed the monster that haunted his dreams.

Kaito blinked at the screen, momentarily speechless. Then he chuckled under his breath. "…Seriously? That counts? Heh. Guess the Fun System really is living up to its name. But it's a good feeling..."

He couldn't help but feel amused—and a little proud. In the original Fate story, Shinji was one of the most hated characters. But this version, this five-year-old boy who hadn't yet been twisted by Zouken's corruption, had just witnessed a real superhero.

And that kind of moment? It could change everything.

Sure, tonight's chaos had been Kaito's doing. But anyone who knew Fate understood: even without him, this father and son would have met miserable ends under Zouken's control. Tonight's disaster, in truth, had given them a new future.

More importantly, the real Shinji—without Zouken's influence—wasn't talentless. Canonically, he was a genius in almost every field except magic. A bright, capable boy with limitless potential.

So now, his "light"—the symbol of his ideal—was a mysterious superhero named Iron Man.

What kind of future would that Shinji Matou create?

Kaito exhaled softly, then muttered with a grin. "I kinda wanna see it."

Unfortunately, once he finished the Fourth Holy Grail War, he'd be leaving this world. Who knew if he'd ever get the chance to return?

Still, the thought made him smile. This was what the Fun System was all about.

Even better, saving Byakuya and Shinji had earned him more points than expected. Though minor characters in the original story, they were still canon, which meant they counted.

Byakuya had yielded 122 Fun Points. Shinji, 185.

Apparently, Zouken's rampage—triggered entirely because of Kaito—had scared them enough to fill the Fun meter completely.

And when Iron Man swooped in to save them, their emotional spike had maxed it out entirely.

All in all, a pretty good night for both heroism and farming points.

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