Night.
In the guest room assigned to Seiji at Tohsaka Manor.
The curtains were drawn tight, not a sliver of moonlight slipping through.
The lights were off in the room, only a single burning candle, giving off a calming fragrance, swayed in the darkness, casting his stretched, twisted shadow against the wall.
Seiji sat cross-legged in the center of the room.
He had already laid down a small soundproofing field and a cognitive interference field, ensuring that no one would detect the "work" to come.
In front of him, an object the size of a palm, wrapped in black velvet, lay quietly on the floor.
He reached out and slowly peeled back the velvet.
A small fragment the size of a fingernail, gleaming with a golden luster, appeared in the candlelight.
The radiance was holy and noble, as if it contained a distant, never-falling utopia.
The aura it gave off even purified, by a measure, the murky mana in the room.
The fragment of Avalon.
In legend, King Arthur's scabbard possessed the power to heal all wounds and even ward off aging. Its true body was a Noble Phantasm that had reached the realm of "True Magic," a genuine manifestation of the Third Magic.
This was the "Holy Relic" he had prepared for Rin Tohsaka. No, for the Saber who would be brought into the world through Rin's hands.
This Holy Relic had not been provided by Waver.
Before coming to Japan, Seiji had obtained it through the Clock Tower's underground black market, exchanging an "improved," priceless alchemical formula with a declining collector.
Waver knew nothing of this.
He thought Seiji was merely a theoretical genius. He had no idea how many dangerous things this "harmless" assistant had quietly prepared for this war.
"What beautiful light..."
Seiji's fingertip brushed lightly across the fragment.
He could feel a warm, soothing sensation passing through his fingertip, as if his very soul were being washed clean.
"A symbol of 'ideals' and 'protection'... It's precisely because of these intangible things that the King of Knights was bound to the past, forever reaching for what she could not grasp."
His eyes turned slowly cold.
"Then let me add something more interesting to this 'ideal.' A little... poison from 'reality.'"
He closed his eyes.
The [Absolute Authority] suppressed for so long within his body began, with the system's aid, to be drawn out with great difficulty, thread by thread.
[Warning! Forcibly invoking sealed authority will impose enormous strain on the host's mind!]
[Confirm execution of "Concept Pollution" protocol?]
"Confirm."
Seiji did not hesitate.
A low hum spread out from him, an invisible force that transcended this world's system of magecraft.
It was a force of... "definition."
It was an authority belonging to "gods," one that said, "If I say it is so, it is so."
With this power suppressed to its limit, he could not directly warp reality.
But for a small, isolated fragment of a "concept armament," carrying out an extremely subtle "backdoor" implant was still within reach, if barely.
His spiritual force took the shape of an invisible, pitch-black probe and slowly pierced into the sacred light of the Avalon fragment.
The process was unbearably arduous and painful.
The world's Counter Force was rejecting his actions with a frenzy.
He felt his soul being pierced by countless unseen needles, every deeper push of his spiritual force like a red-hot brand searing his soul.
Beads of sweat the size of soybeans seeped from his forehead and ran down his cheeks.
But his expression remained calm, even... carrying a hint of enjoyment.
This sensation of standing against the entire world, this pleasure of carving his own mark into the cracks of the rules, was far more thrilling than doing whatever he pleased back in his previous world.
"Found it... the core of the concept of 'utopia'..."
His spiritual force finally touched the most fundamental "definition" of the fragment.
There lay a pure sea of light, woven from "protection" and "faith."
And what Seiji had to do was let fall, into that sea of light, a single drop of poison that belonged only to him.
["Concept Pollution" initiated...]
[Implanting distortion concept one: revision to the definition of "protection."]
[Revision content: the object of "protection" will be subject to latent influence by the host's "affection level." When the host harbors "hostility" toward someone, the concept of "protection" will develop repulsion toward them, causing the healing effect to drop significantly or even fail entirely.]
[Implanting distortion concept two: logical backdoor in "faith."]
[Implant content: when the wielder's "faith" wavers, the energy output of their Noble Phantasm (Excalibur) will become unstable. At such moments, the wielder will give priority to accepting "mental suggestions" from the host, defining them as "the correct path."]
...
The process lasted a full hour.
When Seiji opened his eyes again, his face was as pale as paper, his whole body drenched in sweat, as if he had just been pulled from water.
But those pitch-black eyes of his shone with a frightening light, full of the satisfaction of a great task completed.
He looked once more at the fragment of Avalon.
It looked exactly the same as before.
It still gave off that holy, noble light.
But only Seiji knew that the most fundamental "program code" of this Holy Relic had been rewritten by him.
It was no longer a pure "utopia."
It was... a perfectly tailored "Trojan horse," made just for him.
The Saber summoned through it would, at first, show no abnormalities. She would still be that noble, chivalrous King of Knights.
But her "Noble Phantasm" and her "faith" had already been implanted with a "backdoor" at their root.
A "backdoor" that only Seiji could activate.
"With this, the 'key' is ready."
Seiji wrapped the "polluted" Holy Relic back up in velvet.
Tomorrow, he would deliver it as a "gift," a thoughtful gift from "Teacher Waver's assistant," into the hands of that proud Rin Tohsaka, who knew nothing of the destiny approaching her.
He could hardly wait to see what kind of despairing expression the King of Knights would wear at the most crucial moment, when she discovered that the holy sword in her hand had "betrayed" her own faith.
...
...
According to regulations, before the Holy Grail War officially began, all outside participants needed to register with the Overseer of the ritual.
The Overseer was dispatched by the Holy Church, ostensibly to maintain the order of the ritual, but in reality to ensure that the miracle known as the "Grail" would not fall into the hands of the Mage's Association.
This time, the Overseer was stationed in a church halfway up a mountain on the outskirts of Fuyuki City.
"...Risei Kotomine's son?"
On the way to the church, Waver's expression was grim.
He was driving an ordinary sedan borrowed from the Tohsaka family, with Seiji in the passenger seat.
"The Overseer of the Fourth Holy Grail War was Risei Kotomine. I never had a good impression of him. A textbook religious huckster, all about 'the Lord' and 'forgiveness,' but in truth colder than anyone. I didn't expect his son to be the one taking over this time."
"Teacher, is there anything in particular to watch out for with this Kirei Kotomine?" Seiji asked at his side, his timing perfect, polishing a test tube of alchemical reagent with a soft cloth, looking every bit the diligent lab assistant.
"The files say he was once an 'Executor' for the Holy Church, a butcher specialized in hunting heretics. He later retired for unknown reasons and returned to Fuyuki City." Waver shook his head, his grip on the wheel tightening. "In any case, stay away from him. Nobody from the Church is any good. They and we magi are natural enemies."
"I understand," Seiji answered with a nod.
Inwardly though,Not just "no good." That man is a monster wearing human skin, one who takes pleasure in tasting others' suffering.
Before long, they arrived at the church on the mountaintop.
The church's architecture was archaic and solemn, but for some reason gave off a feeling of cold lifelessness. As if what was enshrined here was not a deity but something far more sinister. The trees around the church grew twisted and crooked, as though silently telling of pain.
Pushing open the heavy wooden door, a mingled smell of aged wood and incense washed over them.
The inside of the church was empty.
Sunlight streamed in through the tall stained-glass windows, but couldn't drive off the chill. In the shafts of light, countless drifting dust motes could be seen.
Only beside the confessional at the very front stood a tall man in a black priest's cassock.
His back was to them. He appeared to be wiping, with leisurely motions, a strangely shaped black short blade with a white cloth. A "Black Key," the standard-issue weapon of the Holy Church.
"Lord El-Melloi II."
The man did not turn around. His voice was low, flat, and devoid of any emotional color, like a block of ice that would never melt.
"Ten years apart. I didn't think you would actually come back."
The man slowly turned around.
His features were as deeply carved as a sculpture, but those eyes were like two bottomless pools of stagnant water, where no ripple of emotion could be seen.
Kirei Kotomine.
"Kirei... Kotomine." Seeing him, Waver's hand instinctively clenched into a fist.
Waver's memories of this man, the disciple of Tokiomi Tohsaka during the Fourth War, were not pleasant.
He had always felt that there was something deeply unsettling about this man.
"I am only here to fulfill my duties as overseer," Waver said coldly. "Here are the official documents from the Mage's Association."
He handed over the documents.
Kirei took them, glanced casually across the contents, and then his gaze passed Waver and landed on Seiji behind him.
In that instant.
Seiji felt as if he were being stared at by a hibernating venomous snake.
The other man's gaze carried no killing intent, not even any emotion. But it was precisely that absolute "emptiness" that gave him a thrill of... finding a worthy opponent.
[Warning! Anomalous soul state detected in target!]
[Target: Kirei Kotomine.]
[Soul essence analysis: 'twisted,' 'pleasure-seeking,' 'empty'...]
[Comprehensive evaluation: a born 'defective' whose sustenance is 'human suffering.']
The system's analysis confirmed Seiji's judgment.
And almost at the same moment, in those stagnant-water eyes of Kirei Kotomine, for the first time, a barely perceptible ripple of something close to curiosity surfaced.
He too had "seen" it.
Though he had no system, with his innate, keen instinct for "the abnormal," he caught the scent of a kindred spirit from the seemingly cowardly and harmless young man before him.
The two men's gazes met in the air for no more than a second.
Yet it was as if some communion incomprehensible to outsiders had taken place.
"And this is?" Kirei spoke, his gaze still locked on Seiji.
"My assistant, Seiji Fujiwara." Waver frowned and stepped forward, blocking Seiji from view without making it obvious, severing the line of sight between them.
"Oh..." For the first time, a faint expression crossed Kirei's face, one that could just barely be called a "smile." It only made his face look more disquieting.
"A soul that... looks rather delicious."
He said it in a low voice that only he could hear.
"...Pardon me, what was that you said?" Seiji raised his head, his face wearing just the right measure of confusion and unease at being watched by someone of higher station.
"Nothing." Kirei withdrew his gaze, his expression returning to that dead-man's calm. "I was only saying, welcome to Fuyuki City. I hope you find what you're looking for here."
With that, he paid them no further mind, turned, and walked into the shadows of the church.
"Let's go."
Waver's face was grim. He pulled Seiji along and quickly left the church that had left him feeling suffocated.
Only once they were outside the church, breathing the fresh air, did Waver let out a breath of relief.
"Remember what I told you, Seiji," he warned solemnly. "Absolutely do not get tangled up with that man in any way."
"Yes... yes, teacher." Seiji nodded again and again, his face still carrying a trace of lingering fear.
But in the depths of his heart, he was sneering.
Don't get tangled up?
How could I not.
Kirei Kotomine... this man is one of the "toys" I've already set aside for this game.