Thanks to Shirou's unrelenting efforts, the investigation progressed... a little faster.
After all, the scenes Shirou had witnessed were already quite blurry to begin with, and he still had to find a way to describe them to others. Naturally, that reduced their usefulness considerably.
However, Illya seemed to have already found some leads. She left the library ahead of them, leaving only Shirou and Rin to continue their work.
As for the two Servants, Archer and Berserker, the latter aside, Archer was currently gathering information on his own outside. As a result, Rin not only had to search through the materials she needed, but also organize the intelligence Archer brought back.
She was busy like a spinning top. Fortunately, Shirou had recovered enough to provide some assistance. Otherwise, Rin would have had to take on the additional task of looking after him as well.
"Rin, Shirou, I found some relevant records."
After the two had been busy for quite a while, Illya returned to the library with a serious expression.
From her explanation, they learned that during the Third Holy Grail War, the Einzbern family had violated the rules and summoned an Avenger-class Servant.
With that revelation, many previously disconnected pieces finally began to fit together.
Furthermore, Illya revealed another important piece of information.
As the Lesser Grail, she had not sensed the magical energy of Saber, Caster, or any of the other Servants who had supposedly been eliminated.
That meant the two of them might not actually be out of the war. They could simply have been captured and restrained.
Or perhaps...
There was another Lesser Grail somewhere within Fuyuki City.
Neither possibility was good news.
The amount of information they had gathered this time was substantial, and it highlighted just how abnormal this Holy Grail War had become.
If Saber had become an enemy, Rin could not even imagine how they were supposed to deal with her. Having a dependable ally suddenly turn into an opponent was troublesome enough, not to mention the addition of Caster.
The difficulty level had practically shot through the roof.
Yet abandoning the situation was not an option. That simply was not how Rin operated.
As a result, she had entered a rather strange state. One moment she would be clutching a book and shouting in frustration, and the next she would fall completely silent.
Even Shirou found himself worrying about her mental state.
Then again, he could understand.
Facing someone like Saber as an enemy...
It was not something he had ever imagined.
On top of that, the Grail itself had already been corrupted. This Holy Grail War had long since changed into something entirely different.
For Shirou, however, that part did not matter much.
He had never intended to use the Holy Grail to grant a wish anyway.
As for the others, he still did not know what Rin's or Illya's wishes were, so he could not really comment.
One thing was certain, however.
The road ahead would be extremely difficult.
One wrong step, and they could easily fall into the abyss.
Was he afraid?
To be honest, yes.
Shirou was still afraid.
But compared to fearing how difficult the path ahead might be, he feared even more the future in which he retreated and could do nothing but watch everything he cared about be destroyed.
That was why he had to move forward.
Or rather, he had to take this step.
It was a demand he placed upon himself.
No one had forced him.
No one had asked him to do it.
It was simply his own decision.
The rest of the night passed relatively peacefully.
Neither Shirou nor Rin went out. Instead, they stayed overnight at Einzbern Castle.
During that time, Rin did not remain idle. She shared all the information and records she had organized with Illya.
Piece by piece, the puzzle came together.
Part of the truth behind the Holy Grail War finally appeared before the three of them—
What they still lacked was the piece concerning the hidden mastermind.
Perhaps such a mastermind did not exist.
But that did not stop them from assuming one did for the time being. Otherwise, too many events remained impossible to explain.
As for possible suspects...
"The Matou family is very suspicious. The Church and the Mage's Association are as well."
That was Illya's conclusion.
It was already morning.
Shirou, Rin, and Illya were gathered around a small table, eating breakfast while reviewing the information they had compiled.
The main purpose was to bring Shirou and Archer, who had not been present for much of the investigation, up to speed on the situation.
At the same time, reviewing everything once more might help them notice anything they had overlooked.
"You might as well have said nothing. Obviously those three groups are suspicious! They are basically all the major magical factions in Fuyuki besides us!"
Having stayed up all night, Rin seemed noticeably irritable.
The fork in her hand had already been bent out of shape by her grip.
"You know that, but Shirou does not. From Shirou's perspective, the latter two should seem much more suspicious, right?"
Faced with Rin's irritation, Illya appeared considerably more composed, though traces of exhaustion still lingered on her face.
"Ah... that is true. But could it be the actions of some individual magus instead?"
Suddenly dragged into the conversation, Shirou nodded honestly.
If he had to choose, he would definitely find the Church and the Mage's Association more suspicious.
After all, he had acquaintances within the Matou family. If possible, he did not want to suspect his friends.
There was also...
That priest.
And the stories Rin had told him regarding the reputation of many magus.
Neither exactly inspired confidence in the Church or the Mage's Association.
Of course, Shirou had considered the possibility that everything was the work of an individual magus.
However, both Illya and Rin quickly rejected the idea.
"We can rule out the Mage's Association for now. None of the participating Masters have direct ties to it. At the moment, the Church seems far more suspicious. We detected a considerable magical energy fluctuation there yesterday."
Watching the others engage in heated discussion, Archer finally offered his own opinion.
Drawing upon what he still remembered, Archer was able to provide a number of suggestions and ideas.
"That damn priest... Since Archer says so, let us investigate the Church's movements first."
After hearing Archer's opinion, Rin paused for a moment before ultimately deciding to treat the Church as a primary suspect.
Normally she would not make such a casual decision, but she was truly exhausted. At this point, she only wanted to get some sleep and find something for Shirou and Archer to do.
After all, Shirou had enjoyed a proper night's rest. He looked quite energetic now. If she did not make use of him a little, she felt strangely dissatisfied.
"In that case, Shirou and I will investigate the Matou family. We will leave the Church to Archer."
Illya still considered the Matou family highly suspicious and planned to accompany Shirou to investigate.
Of course, she was not intending for Shirou to make inquiries as a magus. Instead, she wanted him to approach people he knew personally, namely Sakura Matou or Shinji Matou.
Personally, Illya preferred starting with Sakura. It seemed considerably safer.
"That works. Bringing this kid along would only make things more difficult for me anyway. I will head out first."
Naturally, Archer had no reason to reject the proposal. After nodding, he transformed into spirit form and departed.
Shirou: "..."
It was rather sudden.
Then again, considering it was Archer, it somehow felt perfectly normal.
So the unexpectedly improved attitude Archer had shown the previous night really had been his imagination after all.
Shirou did not object to Illya's suggestion either. After all, this was one of the few areas where he could actually be useful.
Originally, he had planned to go alone and let Illya rest. However, she firmly rejected the idea, arguing that it was too dangerous for an ordinary person like him to approach the Matou family by himself.
Even though the Matou family had fallen from prominence, they were still far beyond ordinary people. No matter how friendly Shirou was with the younger members of the family, that relationship meant little in the eyes of a magus.
Compared to Archer observing from afar, Shirou directly approaching them was actually far more dangerous.
Furthermore, Rider of the Matou family had not yet been eliminated. For Shirou, who did not have a Servant, that was the greatest danger of all.
After she put it that way, Shirou could not really argue.
The plan had been arranged, but once they actually set out, Shirou discovered that he could not contact Sakura.
Her phone could not be reached, and none of the people familiar with her knew where she had gone.
All anyone knew was that she had last been seen on Fuyuki's main street the previous day. According to witnesses, Sakura had looked distracted and absent-minded at the time. Someone had intended to check on her, but after looking away for only a moment, she had vanished.
Even though they could not reach Sakura, the investigation still had to continue.
However, their objective shifted from gathering information about the Matou family's current situation to directly monitoring the area around the Matou residence, much like Archer was doing.
At that point, it became Illya's specialty.
After all, aside from basic visual observation, Shirou knew absolutely nothing about the magical techniques involved.
In fact, not only did he know nothing about surveillance magecraft, he barely understood how surveillance itself was supposed to work. His suspicious behavior nearly resulted in him being reported by concerned passersby.
Had Illya not deliberately acted like a child, making it appear as though Shirou was simply accompanying her on an outing, their surveillance operation might have ended right there.
Illya was remarkably tolerant of Shirou's various mistakes.
Besides, she personally found the whole thing rather amusing.
Since most of the actual investigation and monitoring was being handled through magecraft anyway, there was nothing wrong with the two of them relaxing a little outside.
As a result, they spent the entire morning sitting in an empty lot near the Matou residence.
And they discovered absolutely nothing.
There were no traces of magecraft.
Not even the slightest fluctuation of magical energy.
After spending the whole morning there, even Illya began to feel bored.
She simply rested her head on Shirou's lap and fell asleep.
Shirou did not object.
Instead, he removed his black-and-white coat and draped it over her.
At that moment, the two looked like a pair of siblings with an exceptionally close relationship.
They would have looked even more convincing if Shirou's gaze had not kept wandering elsewhere.
"I wonder if Sakura is alright."
After sitting there for quite some time, Shirou muttered to himself.
When he first learned about Sakura's situation, his immediate instinct had been to find Shinji and ask where she had gone.
Unfortunately, the Matou household phone could not be reached either, which meant he had no way of contacting Shinji.
After carefully weighing his options, he had decided to accompany Illya to the Matou residence first and search for clues nearby.
Yet the Matou house now resembled a dead, abandoned mansion.
Not a single person could be seen.
Every curtain was drawn tightly shut.
This effectively cut off all of Shirou's leads regarding the Matou family.
Far from clearing their suspicions, the situation only made them seem even more suspicious.
Under circumstances like these, finding the entire Matou household completely empty was practically the same as writing I am the mastermind across their faces.
Combined with the troubling reports regarding Sakura's condition, the suspicion only grew stronger.
So many coincidences had piled up that even Shirou could not help becoming suspicious of the Matou family.
"Was that... Rider?"
Just as Shirou was lost in thought, he thought he saw a purple figure standing by one of the Matou residence's windows.
When he narrowed his eyes and tried to get a better look, the purple figure had already disappeared.
The Matou residence.
A purple figure.
When those two facts were combined, Rider was the only possibility Shirou could think of.
Although he had only seen it for an instant, he was certain he had not imagined it.
The curtain on that room's window had been closed the entire time until just moments ago.
Now it was open.
Without hesitation, Shirou hurriedly woke the sleeping Illya and asked her to send one of her familiars to investigate the situation.
"Mm...!?"
Having just woken up, Illya was still somewhat groggy. Swaying slightly, she directed her familiar toward the Matou residence.
The moment the familiar reached its destination, however, Illya suddenly frowned and immediately severed her connection with it.
"Let us head back. I do not think we are going to find any more clues at the Matou house."
Returning Shirou's coat, Illya hopped down from the chair and spoke.
"Did you see something?"
Noticing how serious Illya had suddenly become, Shirou hurriedly asked.
"Rider's Master is dead," Illya replied.
"...Shinji is dead?"
Shirou froze for a moment upon hearing her words.
Although he had completely fallen out with Shinji a few days earlier, hearing news of his death...
He could not help feeling a sense of sadness.
But this was the Holy Grail War.
This was the world of magecracft.
After taking a moment to compose himself, Shirou drew a deep breath and asked,
"Do you think the cause of Rider's Master's death is related to that black phantom?"
"Yes. If even a Master with a Servant died so easily, then the rest of the Matou family probably had no way to resist either..."
Halfway through her sentence, Illya seemed to think of something. She stopped walking and glanced at Shirou.
"Hm?"
Suddenly finding himself under Illya's scrutiny, Shirou let out a puzzled sound.
"It is nothing. I am just surprised that you are calmer than I expected. I thought you would be... more furious, perhaps?"
After observing him for a while and confirming that his composure was genuine rather than an act, Illya withdrew her gaze and continued walking.
"I am a little angry, sure. But there are more important things that need to be done right now, are there not?"
Shirou knew exactly what Illya was referring to.
If it had been the old him, perhaps he would have been consumed by anger over what had happened to Shinji and the Matou family.
But now, there simply was not enough time for that.
He understood the importance of the situation and the order of priorities.
"I see... Shirou, you have become more mature."
Walking ahead of him, Illya pursed her lips for a moment before returning to her usual teasing tone.
"That is a good thing. Keep it up, all right?"
If Shirou had seen what she saw inside that room, he certainly would not have remained this calm.
Still, there was no need for him to witness something like that.
It was enough that she had seen it herself.
After all, it had been a scene disturbing enough to make even her, a magus, feel uncomfortable.