Kiritsugu was also known as the "Magus Killer."
This meant that, in his past career, he had fought against more magi than most ordinary people could ever hope to even meet in their entire lives.
Through these experiences, he discovered the greatest weakness of magi: the carelessness born of arrogance.
When facing combat, they focused only on magecraft. As a result, they underestimated purely physical attacks that did not rely on magecraft, dismissing them as secondary threats.
However, when a magus was not careless and had fully prepared, Kiritsugu had virtually no means of gravely injuring them in direct confrontation—except by using the "Origin Bullet."
Kayneth was without question the strongest magus in direct combat Kiritsugu had ever faced. Yet that was not the most fatal part of the situation.
—Because his opponent also had a Lancer at his side.
At the very instant he leapt out of a blasted hole—
A golden spear shot out from the void, slashing straight toward his back.
Kiritsugu had never before felt death so close.
He was neither a hero nor a warrior, but a killer. He had neither the courage nor the pride to gamble his life against another. His goal was always to carefully, cautiously secure victory and the right to survive with the smallest possible risk.
But this time, he had made himself the bait to lure in the enemy.
Even with anticipation, even after activating his Time Manipulation at triple acceleration in the critical moment, the scorching flames trailing the golden spear still set his side ablaze.
In that life-or-death instant, Kiritsugu hurled a grenade toward Kayneth while rolling tactically into the corridor outside, extinguishing the flames as he put as much distance as possible between himself and Lancer.
Such movements, if against a Servant alone, would have been meaningless.
Servants were far too fast for ordinary humans. Such maneuvering would not even delay death by a few milliseconds.
But this time, his opponent was not alone.
"Hm?"
Lancer was slightly surprised that his foe managed to evade his thrust with such speed. Then he noticed the grenade flying toward Kayneth.
Given the overwhelming difference in power, Lancer chose not to pursue Kiritsugu, who had barely opened a ten-meter gap. To prevent his Master from being dragged into a suicidal exchange, he instead swung his spear and knocked the grenade away.
And just as he thought, with a simple sweep of his golden spear, the grenade was batted out through a window.
It seemed Kiritsugu's plan had been instantly foiled.
From a distance, Kiritsugu sighed.
Servants truly were beings beyond the reach of ordinary men. If his opponent had wanted to kill him, he could have died multiple times in just that instant.
Servants were the essence of history, the embodiment of myth, the prototype of the Third Magic in the present world.
Before such a great existence, Kiritsugu, as a mere human, had no way to fight directly.
For an ordinary man, whether a Servant's strength was great or small was meaningless. Even the weakest elephant could crush an ant without effort.
Thus, from the moment his enemies breached the door, he had already set his strategy.
—He had to sever the magical connection between the Master and Servant. And he already had the means to do so.
"I should be just outside the blast radius by now."
Kiritsugu silently counted the seconds. Then, from around a corner glowing faintly with golden light, he stepped out.
Before him stood Lancer, already fading into particles, his face frozen in surprise.
"You…"
So it worked.
Even as backlash from magecraft tore at him, a faint smile appeared on Kiritsugu's face.
Lancer's magical energy had been supplied remotely by someone hidden in the shadows. While such transmission was safe, it was also extremely vulnerable to interference. That was Lancer's weakness.
An Origin Bullet made severing that magical supply all too easy.
That was the weak point he had aimed for.
"Ahhhhhh—!"
Behind Lancer, Kayneth screamed in unbearable agony.
He had not been careless. He had laid Lancer in ambush below as a backup, while relying on the protection of his Moon Spirit Fluid to force this little rat out of hiding.
For an opponent who had lost the protection of his Servant, and who was nothing more than a scavenger relying on electronics and modern firearms—this was already Kayneth's most cautious battle strategy.
If, against such a foe, he still chose to rely on a Servant to launch a sneak attack, then he never would have stepped foot into this castle in the first place.
Yet this pride had still cost Kayneth dearly.
The grenade thrown earlier had merely been a decoy to draw his attention. But it was also a genuine Origin Bomb—a desperate gamble with his life. Fortunately, his luck was good today.
The true Origin Bomb that mattered had already been tossed into the rubble below that hole when Kiritsugu leapt down using his Time Manipulation.
Its mechanism was not so different from an ordinary grenade, and because of its special explosive structure, the sound it produced was almost imperceptible. Yet its effect was the same as an Origin Bullet.
Within its spherical blast radius of ten meters, a magus would have their magical circuits severed and forcibly reconnected, causing the circuits throughout their body to short-circuit and run wild.
The highly condensed Origin Bombs did not need a direct hit. Simply dispersing in the air was enough.
In other words, this was a specialized tactical weapon designed as a countermeasure against magi.
Against a powerful magus like Kayneth, it was a carefully prepared area-of-effect killing tool. Due to the rarity of the materials, Kiritsugu only had three of them in total—and in that instant, he had already used two.
"Still, my luck is good today."
But he had clearly underestimated Kayneth's skill in magecraft.
Just as Kiritsugu thought Kayneth had been gravely injured by the Origin Bomb—
"Scalp!"
With a murderous shout, the mercury unleashed a fatal strike.
At the sight of the blade of mercury whistling toward him, Kiritsugu was shocked and only managed a partial dodge.
Now less than ten meters separated him from Kayneth. For him, that distance was already the limit.
Because he himself was also within the blast radius of the Origin Bomb, he dared not use magecraft to invoke Time Manipulation.
But Kayneth's magical circuits were far more resilient than he had imagined. Unlike the direct impact of an Origin Bullet, the Origin Bomb traded focused lethality for area damage. It was far weaker in terms of killing a single target.
This miscalculation came at a terrible price—
As the mercury blade slashed past, blood sprayed. His right arm was severed completely.
There was no time to ponder how Kayneth, whose magical circuits should have been rampaging from the Origin Bomb, could still control his Mystic Code.
Kiritsugu fired his submachine gun with his left hand.
Though Kayneth was wracked with pain, the Moon Spirit Fluid once again faithfully displayed its function. The defense membrane unfolded instantly, blocking the hail of 9mm rounds just as before.
History repeated itself.
Kiritsugu drew his Contender with his remaining left hand and fired a shot straight at the center of the semicircular mercury membrane.
The Moon Spirit Fluid automatically reshaped itself into the optimal defense against machine-gun fire. But the Contender's bullets were over 2.5 times faster than 9mm rounds, and more than seven times as destructive.
The mercury's speed came from pressure. While it could spread quickly into a thin membrane under pressure, reverting from membrane back into dense block under the same pressure was impossible. That was the limit of fluid mechanics.
Thus, when faced with sudden, overwhelming firepower, the mercury could not respond quickly enough to form a strong defense.
The defense would be pierced, and that one shot would devastate Kayneth's already collapsing magical circuits—
He was about to complete an almost impossible reversal!
Yet the very next moment crushed Kiritsugu's hopes completely.
Standing just beyond the shattered mercury wall was a black-clad woman, calmly raising one hand.
Between her fingers, she had caught his prized Contender's bullet.
The one who had interfered in the battle between the two was none other than Satsuki.
She loosened her fingers slightly, letting the massive bullet drop to the ground with a clang clang of metal striking stone.
Then, lifting her eyes just a little, she cast a faint glance at the man before her.
With only that glance, Kiritsugu Emiya suddenly realized his entire body was immobilized. Even the bleeding at the severed stump of his right arm had stopped.
Beads of sweat rolled down his forehead. Though his face remained expressionless, the deep sense of helplessness and despair in his heart was laid bare before Satsuki at a single look.
"It seems that even with the help of a Servant, you still ended up being outplayed." Satsuki turned her head toward Kayneth. "People must experience failure in order to grow. Perhaps, after this searing defeat, a man like you—who is not entirely a fool—may make some progress."
"I… I…"
Blue veins bulged on Kayneth's forehead. After his outburst of rage, he immediately realized the condition of his own body. Before things could worsen, he decisively cut off the external supply of magical energy.
The Moon Spirit Fluid collapsed with a crash into a pool of liquid mercury.
Having done this, he could no longer suppress the pain within his body.
With a guttural cry, he vomited a mouthful of blood onto the floor.
The agony surging from every part of his body was joined by the despair of sensing the short-circuits among his magical circuits.
Negative emotions corroded his heart like acid, eating away at him bit by bit.
At the same time, a deep sense of humiliation and self-doubt left him speechless…
He was one of the foremost magi of the Clock Tower.
It was undeniable that he bore the pride earned from his past talents. Yet in this battle, he had not underestimated his opponent.
Normally, he would never allow emotions to shake his composure—especially not in a contest of real battle.
He had brought forth his greatest Mystic Code, timed his Servant's cooperation precisely.
This had been his full effort—short of entrusting the entire fight to his Servant alone, there was nothing more to be said of his arrangements.
In truth, if this had been a secret duel between first-rate magi, Kayneth would not have been consumed by anger. He would have marveled at and admired his opponent's skill, calmly assessing their true worth, and then responded with magecraft equal to the opponent's secret art.
But—
The searing pain flooding his body had taught him what it truly meant to partake in the "Holy Grail War."
What's more, he had even dragged his betrothed, Sola, into this war.
How arrogant. How reckless.
"Impossible… I won't lose… I won't lose to the likes of him!"
Thump—
With a light sound, Satsuki struck him unconscious. She had no time to indulge this man in his lamentations. But he could not die yet—not while her battle with Karna had yet to begin.
Then, Satsuki silently turned her gaze upon the man called Kiritsugu Emiya. With her Tenseigan, she saw clearly into his past.
"What a pity… truly a pity."
That was her only judgment of him.
At the same time, Kiritsugu realized he could speak again, though the rest of his body remained immobile.
"You won't kill me?"
"Whether you live or die makes little difference to me," Satsuki said coldly. "So long as you do not obstruct me, I have no interest in deliberately crushing an ant."
"Then why leave me here? What are you trying to do?"
"Isn't it obvious?" Satsuki cast her gaze toward the window. Several hundred meters away, Irisviel and Maiya Hisau were hurrying toward the castle. "You are bait, of course."
As soon as she finished speaking—
A new figure appeared between Satsuki and Kiritsugu.
Radiant with noble bearing, crowned with the diadem of stars, holding the invisible holy sword.
Her emerald eyes burned with defiance, her heroic presence seeming to ignite the very air.
From atop the rubble, Satsuki lowered her gaze slightly at the knight who glared up at her. The corridor between them was bathed in cold moonlight, the silent moment resembling a perfect scene that none could bear to break.
Yet upon noticing her former Master's grievous state, the Knight King could no longer remain calm. She raised one hand, releasing a portion of Avalon's radiance to him. At once, his injuries began rapidly healing. However, since his arm had been severed, she could not completely restore him here.
At the same time, she noticed Lancer's Master lying unconscious behind Satsuki.
The traces of an Origin Bomb's detonation still lingered in the air. With her Instinct, Saber had little trouble deducing what had transpired.
"King of Knights, Artoria Pendragon."
Watching the other's movements, Satsuki did not interfere. Instead, she softly spoke her true name.
"I did not come here to fight you. I only have one question I wish to ask."
"What question?"
Though deeply anxious, Saber bore Avalon within her. Even having once witnessed Satsuki's world-shaking power, her eyes showed no fear.
"Before you were summoned into this world—do you still remember those circumstances?"
"The circumstances before I was summoned?" For an instant, the Knight King of Britain's eyes flickered with memories of the past. But soon her gaze turned resolute once more. "That is my private matter. It has nothing to do with you."
Nothing to do with me? It seemed that not all Servants, unlike Goetia, understood the true purpose behind their summoning into this war.
—"Saber, how is Kiritsugu?"
A woman's voice carried from outside the castle.
It was Irisviel and Maiya Hisau. While Satsuki and Saber faced each other, the two had already arrived near the castle.
From outside, they could see Saber standing in the corridor, confronting Satsuki.
"Iri, Kiritsugu's condition is poor. Take him away quickly. I will hold her here."
With that, Saber raised the invisible sword in her hand and swung it toward a wall.
In the blink of an eye, the wall was cleaved open. Casting a brief glance back at Kiritsugu, she immediately turned her full attention upon the Servant before her.
Yet her words had already revealed her concern for Kiritsugu.
"This is the third floor. Can you manage the jump?"
"No problem."
The persistent sense of loss of control that plagued Kiritsugu's body had been dispelled by the Knight King's healing Noble Phantasm.
But when his gaze fell upon the intruding Servant, it carried only heavy suspicion—what was her aim? She had interfered in the battle, yet harmed neither side's Master.
Her attitude was unlike that of one who truly stood upon the battlefield.
Yet these were questions for which he could never find an answer.
With agility beyond that of ordinary men, Kiritsugu leapt from the third floor with his severed arm in tow, reuniting with his family under Saber's protection.
But before he could breathe a sigh of relief, another figure emerged from the depths of the forest, stepping into the moonlight before them.
At the sight of this figure, Kiritsugu's heart sank.
—It was Kotomine Kirei, the very opponent he least wished to encounter in this war.