In the Alps of southern Germany lay the territory of Einzbern Castle, where the Einzbern stronghold, "Winter Castle," stood.
Inside Winter Castle, a little white-haired girl leaned against the window and gazed outside.
She was waiting for someone, someone very important to her. Ilyasviel still remembered what her father had told her a year ago:
"Illya, your mother and I are going to do something very important. We'll be back in about a month, and once we return, we can stay together forever."
That one month had long since passed. Illya had already waited for a year, yet she still had not seen that tall figure pass through the walnut grove where they had once counted new walnut shoots together.
"Kiritsugu... liar! You clearly said you'd be back in a month! Kiritsugu, you liar!"
Though she said that, her body honestly remained pressed against the window. She was still waiting, afraid that if she turned away, she would miss the figure she longed to see day and night.
At that moment, outside the walnut grove beyond Einzbern Castle, a man was checking his equipment. He loaded Origin Bullets one by one into his most trusted Mystic Code, the handgun Contender, which possessed rifle-like performance.
Those bullets had been made from powder ground from his own ribs. Just like his name, Kiritsugu—cut, bind. That binding did not mean restoration. For example, if a severed thread was joined back together, the thickness at the knot would change.
In other words, the act of "cutting and binding" would cause irreversible "alteration" in its target.
This was Kiritsugu's second time coming here. The last time, the head of the Einzbern family—his wife's "grandfather," Jubstacheit von Einzbern—had refused to open the barrier for a failure like him who had not brought back the Holy Grail.
But as a father, Kiritsugu Emiya still could not let go of his beloved daughter. This time, he had decided on a different approach: force his way into Einzbern Castle!
Kiritsugu truly had the ability to do so now. In other timelines, after he destroyed the Holy Grail, he had been tainted by Black Mud. Then, in order to save Shirou, he transferred Avalon into Shirou's body and suffered further erosion from the Black Mud. His body had grown weaker and weaker, the Magus Killer's strength gradually fading, until he died without seeing Illya again.
But this time, Avalon was still inside Kiritsugu's body, and his skills had not declined. His goal was clear this time: break into Winter Castle and reclaim his daughter.
"Alright, I'll infiltrate it like this!" After checking his equipment once more and confirming that nothing was wrong, Kiritsugu Emiya stepped forward, preparing to enter the walnut grove where he had once played with Illya.
But then, a voice he never expected called out to him—
"Wait, old man!"
Only one person called Kiritsugu Emiya by that name: his adopted son, Emiya Shirou, whose strength, mind, and appearance were completely mismatched.
"Hm, Shirou? Why are you here? Didn't I tell you to—"
"Watch the house, right? I just happened to run into you while out for a walk. No need to be so surprised, is there?" Shirou calmly interrupted Kiritsugu.
That was one hell of a walk—from Japan all the way to Germany!
That was what Kiritsugu thought, but he did not say it—he had no right to.
When Kiritsugu Emiya had been a little older than Shirou was now, he had shot his own father, then flown all over the world with his adoptive mother Natalia, taking jobs and killing people. One strike, one kill.
Compared to that, Shirou flying from Japan to Germany on his own was practically nothing. At least he had not personally shot his own father.
As for whether Shirou might be discovered by a mage with ulterior motives, Kiritsugu had never worried about that at all.
Shirou was very strong. If his strength were expressed using a Servant's parameters, then aside from Luck, which could not be measured, and Noble Phantasm, which could not be assessed, his other four parameters could all reach A rank.
Ordinary mages could not contend with Servants. Even merely similar power was the same. That was Kiritsugu's personal experience from participating in the Holy Grail War.
As long as Shirou did not provoke some ancient mage family full of old monsters, there would be no problem at all.
"If you're here, what about the house?"
"Don't worry! Isn't Fujimura-sensei there? I asked her to watch the house for us." Shirou promptly brought up Fujimura Taiga. "She seemed pretty happy to help us watch it!"
"No, hearing you say that makes me even more worried!" Kiritsugu could not help breaking out in a cold sweat.
"Huh? Is it really okay for you to say that about Fujimura-sensei, old man?" Shirou blinked.
"It's nothing. Taiga is just that kind of person." Kiritsugu remained perfectly calm.
At the same time, far away in Fuyuki, Fujimura Taiga suddenly sneezed. "Achoo! Hm? Is someone badmouthing me?"
"Hoh~ Fujimura-sensei really is unlucky to know you! Anyway, old man, you have another daughter, right?"
"You little brat, already taking someone else's side?"
"Don't deliberately change the subject, old man. I have proof!" Saying that, Shirou pulled a photograph from his pocket. It was a family portrait of Kiritsugu, Irisviel, and Illya!
"I found this in a castle on a mountain not far from Fuyuki. The man in it is you, isn't it, old man?"
"How did you find this?" Seeing the photograph, Kiritsugu was the one who lost his composure. He remembered that it had gone missing during the Fourth Holy Grail War.
"The adult woman in this photo looks very much like the girl who's about my age. Judging by their ages, they should be mother and daughter or something like that. But since you also look younger in the picture, this girl should be around my age.
"Then there's the way you look at this girl, old man. It's about the same as how you look at me, so this girl should be my older sister. Am I right, old man?"
At Shirou's current age, with that chain of reasoning, if he put on a pair of glasses and added the right background music, he would be overflowing with Conan vibes.
"That deduction was pretty accurate, Shirou. Are you planning to become a detective when you grow up?"
"Who would ever become something like that?!" Shirou turned away and spoke disdainfully, but paired with his childish face, it only made him look adorable.
"But the real key is this—" Shirou pointed at the background of the photograph: a walnut grove, exactly like this one. "The two of them are here, aren't they?"
"If possible, I really didn't want you to know about this, Shirou." Since he could no longer hide it, Kiritsugu simply came clean. "The adult woman in the photograph was Irisviel von Einzbern, my wife. You should have called her Mom too, but she's already dead.
"As for that little girl, you should call her your older sister. Her full name is Ilyasviel von Einzbern... What's with that look, Shirou?"
The look Shirou gave Kiritsugu made his hair stand on end.
"With a ridiculously fancy surname like that, old man, you married into her family? You're a live-in son-in-law? That's so lame!"
"Sh... Shut up!"
"Ooh, tsundere! But a tsundere man isn't cute at all!"
"..."
"So, what happened next?"
"That's all!"
"Huh? How can that be? There should be some really interesting story, shouldn't there?" Shirou's eyes were full of gossip.
"That's all means that's all!"
Stare~~
"...Fine. Illya is being kept here by Irisviel's grandfather right now, and I'm planning to infiltrate this place and bring her back." Unable to endure Shirou's utterly blank, dead-man-like stare, Kiritsugu finally relented.
"Interesting. Then count me in. I'm really strong, you know, old man." Shirou clenched his little fist and raised it above his head, flashing a brilliant smile.
"I knew this would happen!" Kiritsugu held his forehead, wearing a pained expression.
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