Sakura Matou's eyes went wide, so stunned that she couldn't say a word.
Was she dreaming?
Everything that had happened tonight was simply too unbelievable.
No matter how she looked at it, it should have been a nightmare.
And yet, the warmth at her shoulder, the gentle strength of Shirou's arm around her, told her that none of this was a dream.
And besides… even if it really was a dream, Sakura Matou thought dazedly, it definitely wasn't a nightmare.
"We're getting out of here."
The boy's low whisper snapped her out of her thoughts.
"Huh? Eek!"
Sakura Matou let out a startled cry as Shirou suddenly swept her up into his arms, carrying her princess-style.
Then he broke into a run without even looking back.
"You damned brat! You dare take what belongs to me… Don't run!"
The old Magus's bloodshot eyes flew open in rage as his body dissolved into a swarm of insects and surged after them.
If this had been Shirou Amamiya at his peak, he naturally would not have cared in the least about an insect-user like Zouken Matou.
In "Britannia," even some random rural fairy could match a human Magus in combat ability, not to mention the calamities that even fairies avoided.
Among those black enemies, insect-type calamities had been especially troublesome for the savior party.
The reason was simple. The moment Morgan faced insects, she went berserk and became completely useless in battle.
It was easy to imagine how much Shirou had suffered cleaning up after her, and how deep his grudge against vermin had grown.
There had even been a time when, after burning hordes of caterpillar-type calamities to death in a night battle, he ended up with the title of "Pest-Exterminating Knight."
Unfortunately, Shirou was only seven years old now. His body was still immature, and he had never undergone any systematic training.
Just projecting the [Blades of Chaos] had already consumed most of his mana, and burning down the insect pit had squeezed nearly all the rest out of him.
Fortunately, his opponent was in no better shape.
Zouken Matou's main fighting power came from that insect pit. At this point, both sides had effectively traded away their core resources.
Shirou ran from the workshop carrying Sakura Matou in his arms, while Zouken Matou chased after them, cursing all the way.
"You ungrateful little brat! Who do you think took you in?!"
With the accumulation of centuries destroyed in one stroke, Zouken Matou was left with nothing but regret.
He had secretly investigated Shirou Amamiya before and already knew how the boy had met his grandson.
But he had never taken it seriously.
Even knowing Shirou was the type of brat who couldn't stand evil and hated wrongdoing on sight, he had still allowed him to stay in the mansion because he found it amusing.
"Brat, do you really want to become a hero of justice that badly?"
Zouken Matou snarled, half mad with rage.
"I'll use insects to control your body and make you violate the daughter of the Tohsaka Family! I'll show you what true despair is!"
That pool of lust worms was not only Zouken Matou's source of power, but also the very foundation sustaining his physical body.
Now that he had lost his nest, the old Magus did not even have enough lifespan left to survive until the Holy Grail War sixty years later, let alone beyond that.
For Zouken Matou, the wish to "keep living" outweighed almost everything else. That was why he had flown into such a rage that he lost all reason.
Boom!!
The passage leading from the workshop to the mansion collapsed in the wake of an explosion.
"Gahhh!"
Zouken Matou let out a miserable scream.
Caught completely off guard, he was buried under the massive chunks of stone and rubble crashing down from above.
This had been arranged in advance by Shirou Amamiya. He had planted homemade earth bombs in the ceiling of the passageway.
Demolition blasting was a high-level explosive technique mainly used to bring down large buildings.
By destroying the most critical supporting point in a structure's strength with a single precise blast, the building's own weight would crush the entire thing inward.
With the smallest possible amount of explosives, it could reduce a building to rubble more efficiently and more reliably. It was destruction elevated to an art.
But what Shirou Amamiya had done here was the exact opposite of demolition blasting.
He only wanted to delay his enemy, not blow the entire mansion sky-high, so the amount of explosives and the blast points had been chosen with extreme care.
Using explosives underground without affecting the structure above was clearly a level of explosive control even more advanced than ordinary demolition work.
Naturally, that too was one of the skills he had honed in "Britannia."
"Damn it…!"
A few seconds later, Zouken Matou crawled out from the rubble, covered in dust.
No matter how he thought about it, he couldn't understand how Shirou had managed to sneak in tonight, avoid the surveillance of the Blade Wing Insects, and plant explosives at the same time.
Of course, he couldn't possibly figure it out.
Because the explosives hadn't been planted tonight.
They had been placed much earlier.
On the very first day Shirou stayed at the Matou residence.
That night, when he secretly slipped out to explore the workshop, he had "incidentally" left behind a small gift for the insect user.
A workshop is a Magus's domain.
Within their own workshop, a Magus is effectively invincible. So Shirou had concluded that if he ever had to fight Zouken Matou, he would need to get as far away from that place as possible.
The explosives had only been prepared as a precaution.
He hadn't expected they would actually come in handy.
Meanwhile—
After being toyed with again and again, Zouken Matou's fury reached its peak.
His hunched body trembled as the insects within him writhed, and he glared ahead at the two figures—
"?"
Shirou Amamiya was gone.
Only the girl stood quietly at the end of the passage.
By the time he realized it, it was already too late.
"Shhk!"
Shirou slipped out from the darkness behind the old Magus and slashed toward his neck.
Zouken Matou's head flew off, rolling across the ground.
Without pause, Shirou followed up, bringing his second strike down diagonally from the left shoulder.
The blade cut cleanly through.
The monster that had ruled the Matou family for centuries was split in two without resistance… or so it seemed.
In the next instant, the old man's body burst apart into a massive swarm of Blade Wing Insects, surging toward the red-haired boy like a black storm.
"Shirou-nii-san!"
Sakura Matou cried out.
As expected, ordinary physical attacks had little effect on Zouken Matou.
But Shirou remained calm, as if he had anticipated this all along.
He allowed the insects to bite into his skin, releasing his grip on the chain blade as he thrust his right hand straight into the swarm.
As though searching, he grasped one of the insects.
"Found it."
"Shhh—!"
In an instant, the entire swarm froze in place, as if time itself had stopped.
Zouken Matou's small body housed an enormous number of insects, well over a thousand, densely packed throughout the area.
And yet, from among that swarm, Shirou had instantly picked out the leader.
The one brain worm that carried Zouken Matou's consciousness.
It was a near-miraculous feat.
Partly thanks to the continuous effect of his "Mystic Eyes of the End," and partly due to the sharp instinct forged through countless battles, the ability known as "Mind's Eye (True)."
Within Zouken Matou's "life system," the brain worm functioned only as a central nervous hub. It had no real means of defense, because he had never imagined anyone would seize his true body alive.
Shirou simply injected a trace of mana into the brain worm and, using a basic spell, took control of the entire swarm.
"Alright… let's try a command."
The red-haired boy spoke calmly as he tore off the wings of Zouken Matou, the brain worm.
"All worms except the old man… kill yourselves."
Crackle…
A rain of black insects fell through the underground passage, their shattered bodies quickly carpeting the floor.
And just like that, the battle was decided.