The day another Illya was born

[Shirou POV]

"I'm sorry, Shirou-san."

"No, it's okay. Getting hit is nothing new for me. If only Miyu could understand..."

After getting punched by Sella and chased out of Ilya's room, I was talking to Miyu in front of the room, who finally understood the misunderstanding thanks to Ruby's testimony. There's nothing I can do about Sella. I can't tell her about Ruby.

Meanwhile, Sella, who thought that I couldn't be trusted with Ilya, was in the middle of waking her up. I was fortunate to clear up Miyu's misunderstanding during this time. That gaze from Miyu really did some damage to my heart.

"So, what brought you here, Miyu? Usually, you wait outside."

"Well, I thought it might be nice to come and pick her up once in a while. Was it bothersome?"

"No, not at all. Feel free to come anytime."

"I'm glad."

While we were having such a conversation, the door behind me opened and out came Sella with her cold gaze. And behind her, there was Ilya with a confused expression on her face. She probably couldn't understand what was happening.

"...So you're not only a siscon but also a lolicon?"

"Hey, stop it, Sella! Ilya can hear you!"

Sella made an outrageous statement. She probably misunderstood that I was hitting on Ilya's friend Miyu as well. The false charges couldn't get any worse. My image in Sella's mind was becoming something outrageous.

"Oh, Miyu's here. Good morning, big brother, Miyu."

"Good morning, Ilya. I came to pick you up today."

Beside me, who was having a tense confrontation with Sella, my sisters were having a peaceful exchange. This house is peaceful as usual today...

.........…

"Good morning, Issei."

"Ah, good morning, Emiya."

After managing to soothe Sella, I arrived at school as usual with Ilya and Miyu. As usual, I put my bag on my seat in my own class and exchanged greetings with Issei.

"Good morning to you too, Rin and Luvia."

"Eh, y-yes. Good morning, Emiya-kun."

"Good morning, Shiro."

It's been two weeks since that incident. A lot happened with these two, and we've become friendlier than before. Well, for me, those events were a series of troubles. At first, convincing these two, who didn't come to school due to circumstances...

We ended up spending regular school life together, but for some reason, I kept having physical contact with these two... Because of that, Rin became a little stiff, and Luvia started calling me Shero for some reason.

Due to these and other things, my reputation in the class took a hit, but it's okay if these two can enjoy normal school life. It's better than when they were upset about their unwilling school life.

When I talk to these two, some people get a subtle atmosphere. Like Issei, who doesn't get along well with these two, and Moriyama in the seat next to me, who looks teary-eyed.

"Uhm, good morning, Moriyama."

"Ah, um... G-good morning, Emiya-kun."

The person most affected by Rin and the others officially joining the class is probably this Moriyama Nanami. She was the biggest victim, having been caught up in the two's fights and passing out, or being covered in frogs and passing out...

Because of that, Moriyama has become scared when she sees Rin and the others. Poor thing. All because I couldn't stop them. So at least, I want to do anything I can for her...

"Are you okay, Moriyama? Is there something you want, or something you want me to do?"

"Huh!? Um, Emiya-kun, you would do anything...?"

"Yeah, anything I can do."

"Uh, well... then, I want you to go shopping with me next time, maybe..."

"That's fine, anytime. Carry your bags? I'm used to that because of my sisters."

"N-not like that... I want to go shopping together... um..."

"Che..."

When I asked Moriyama what she wanted, she turned red and nervously made that request. Then, Rin and Luvia, who were watching Moriyama for some reason, clicked their tongues lightly.

Why though? Where in that conversation was there a reason to make such a sullen face? Tilting my head at their incomprehensible reactions, I start to arrange a shopping schedule with Moriyama. Maybe on Sunday?

"Is this Sunday okay?"

"Y-yes! I'm looking forward to it, Emiya-kun."

"Haha, I don't think I can provide anything that interesting, you know?"

"That's not true. I'm really excited..."

"...This woman..."

When she's looking forward to it that much, it motivates me too. I should think about not just accompanying her to places she wants to go but also bringing something or planning something on my own. Like a lunch box, for instance.

I might consult with Ilya and find places that girls would like. But considering the age difference, Ilya's preferences may not match Moriyama's, so it might be better to consult with Sakura, who is closer in age.

As I thought about such things, I failed to notice the disgruntled aura bursting from Rin and Luvia next to me.

.........…

"Hey. Tohsaka, Luvia."

"Huh, what is it, Emiya-kun?"

"What can I do for you?"

The time has flown since the morning, and it's now nearing the end of lunch break. Tohsaka and Luvia, who had been absent from the classroom until a while ago, seemed to be acting strange. The fact that these two were together was already strange.

Moreover, the two who returned did not seem to be about to argue, and sat down at their own seats acting suspiciously. It's odd. Their behavior, blatantly avoiding me, also bothers me. As expected, when I addressed them, they reacted like this.

"Did something happen?"

"Uh... n-no, nothing like that!"

"That's right. Please don't worry..."

It definitely feels like something happened. And something that they need to hide. Considering the true nature of these two, it's probably related to magic. And if it's something particularly bad for me to find out about... could it be, Ilya?

"...Is this related to Ilya?"

"Yikes! There's no way something like that could happen! What are you talking about?"

"Oho ho ho. Shero, you say funny things!"

That confirms it. Something has happened related to magic, and Ilya is involved, isn't she? No, think carefully, me. These two are, after all, magicians with some common sense. When they argue, it blows to the far side of time and space, though.

It's impossible for these two to actively involve Ilya in things related to magic. That means, in this case, it's something special that Ilya has. It's natural to think they need that.

Speaking of something Ilya has that these two would need... ah, I see!

"Is it Ruby?"

"H-How did you know?!"

"Hey, Tohsaka Rin! That's pretty much a confirmation!"

"Ah, that's bad..."

Bingo. Even so, Tohsaka can be absent-minded in strange places. She's not good at keeping secrets. Luvia isn't particularly skilled at it either, but Tohsaka's inability is more pronounced. Well, that aside, let's hear the details.

"I want you to tell me the details. After school, on the rooftop."

"Ha, understood..."

"We have no choice, do we?"

Feeling a premonition that another troublesome event may be starting, I attended the afternoon classes.

.........…

"So, this is how things are turning out..."

"In other words, there's going to be a problem ahead, and we'll need Ruby to fix it, right?"

"It seems so."

More time has passed since then, and I'm now walking through the forest. I'm explaining the situation to Illya, who was abducted by a car while trying to leave school. I don't fully understand it myself, either.

"It's not so much Ruby, but rather, a large amount of magical energy that's necessary. The Kaleidostick possesses infinite magical power."

"We will use it to perform a large-scale ritual to stabilize the ley lines."

"Hmm."

"I've already explained this to Emiya-kun. The truth is, even though we've collected all the Class Cards, the town's ley lines haven't returned to normal. According to the Great Master, it's possible that the Dragon Hole is blocked. So..."

"We will expand it through the ritual. However, the ritual requires highly compressed magical energy."

Listening to their explanations full of magical jargon was challenging, but I managed to grasp the basics of what they were saying. I had heard that the town was in danger because of the cards.

Despite having collected all of them, the anomaly hasn't been corrected (Tohsaka said it should naturally return to normal). If the anomaly hasn't been corrected, there's a high likelihood of a problem. And we're trying to fix that.

The implication is that a large amount of magical energy is necessary to fix this problem, and for that, the Kaleidosticks held by Illya and Miyu are needed. I understand the situation. It's not someone else's problem to us, so it can't be helped.

"I really didn't want to involve Illya and the others anymore..."

"Ideally, we would have called for a lot of reinforcements and solved the problem ourselves. But when we requested reinforcements, we were told there would be no problem because we had been given the Kaleidosticks..."

"It can't be helped since we've kept it a secret from the Great Master that we've been released from our contracts with Ruby and the others!"

Ruby:『Gosh, you all are truly incompetent.』

"Shut up! If you re-contract with me, everything would be resolved!"

"Hahaha..."

So that's the situation. Well, it's not something easy to say. After having a big fight with Luvia, and the stick getting fed up with it, we ended up involving an unrelated elementary school student who was chosen as the new master.

So when she came back during lunch break, that's why she had such an awkward expression. And I, being Illya's older brother, felt sorry for involving my sister again. Upon hearing the situation, it makes sense.

"Is Miyu okay with this?"

"I have no problem at all."

When I confirmed with Miyu, who was walking a bit behind Tohsaka and the others, she said that. It's very much like Miyu, but is it bad that I want a more childlike response? She's too obedient.

"You can be more stubborn and complain, like Illya."

"He, hey, brother! That makes me sound like a disobedient child!"

Illya is clearly a child, I thought, but I didn't say it out loud. I know from experience what happens when I say that. In my view, it's okay to behave like a child because she actually is one.

"Well, let's put aside what Illya does for now. I'd be happy if you voiced your complaints. It would give me a reason to work harder. I think that's more endearing."

"Endearing... in that case, I want to see the sea."

"Hmm. Miyu, you've never seen the sea? Then, summer vacation is in a month. How about I take you there?"

"Really?"

"Yeah. Illya will go too, right?"

"Yeah, of course!"

"That's settled then. Don't hold back."

"Yes, I'm really happy..."

Saying so, Miyu smiled genuinely, her eyes glistening with tears. Well, I'm glad she's happy, but isn't this a bit too much? Miyu's feelings are often quite heavy.

We walked in silence for a while. Tohsaka and Luvia were leading the way, followed by Miyu. Illya and I were walking side by side at the back. Oh, right, about the dream I had this morning...

"Hey, Illya."

"What is it, brother?"

"Well, I wanted to ask you something. Do you remember going camping about seven years ago?"

"Yeah, I remember. What about it?"

Good, it seems Illya remembers too. I wanted to ask her about it but forgot due to the morning's commotion. It's just a dream, but the discrepancy in memory bothers me.

"That camping trip, our parents took us to help us get along better, leaving out Sella and Liz to ensure we could spend as much time together as possible."

"That's right. And because of that camp, we were able to open up to each other..."

"That's right. So do you remember what exactly brought us closer?"

"Huh? ... Hmm... Not exactly. I was only about four years old then. Didn't we just gradually get closer by playing together? I mean, we always wanted to get along..."

"Is that so?"

I see. Illya was really young, so she might not remember clearly. Hearing Illya say that makes me think that might be the case. But then, what was that vision?

"...Hey, didn't something happen at that time?"

"What do you mean?"

"Well, for instance, didn't I get hurt, or didn't Illya cry?"

"Ah. That's about...that incident, right?"

While I was trying to find a clue from that mysterious vision, Illya seemed to recall something. Oh, so that really happened? Was it just something I had forgotten? I waited for Illya's words.

"On the way back from the river, there was a cliff about 3 meters high. I was about to fall from it, and you shielded me, fell down, hit your head and fainted, didn't you? I cried at that time. Don't you remember?"

"...Did such a thing happen?"

"It did. I was really sad at that time. But I was happy that you protected me. In retrospect, that might have been the trigger. I thought, this person would protect me..."

"...I see..."

So, just because I hit my head, I couldn't remember that trigger. That vision was from that time, huh. I see. So, that's how it was. Okay, I'm convinced. But still, that was...

"...About 3 meters, huh?"

"Yeah. For me, who was about 4 years old at that time, it felt much higher."

I see. I was about 10 years old at that time, too. Maybe it felt higher because of the image in my mind. Besides, that was a dream. It was not reality. It must have been exaggerated because it was a dream. It must be so.

The chronological inconsistencies of the events that followed aren't so strange if we consider it was a dream. In that dream, our awkwardness didn't change even after we returned from the river, and Dad and Irisviel went out for a walk.

But if what Illya said is true, I should have no memory of what happened after I fainted. My memory may have become vague because of the confusion, so I should trust Illya's memory more.

"But why did you ask about what happened at that time?"

"Well, actually, I had a dream about that time this morning. The discrepancy in memory bothered me..."

"'We've hit a bottomless swamp!'"

"Lu, Luvia-san! Rin-san!"

"...Huh?"

While I was talking with Illya, I heard a comical voice from ahead. When I looked, Rin and Luvia were stuck in a bottomless swamp, and Miyu was trying to pull them up by Luvia's hair.

"Why are you pulling my hair, Miyu?!"

"Emiya-kun, Illya! Don't just stand there talking, help... (bubbling)"

"...Sigh."

"These people are..."

Ruby:『pukukuku...They are like comedic entertainers, aren't they?』

After that, we had quite a struggle pulling them up. Because of that commotion, my conversation with Illya was interrupted.

...............…

[Illya POV]

"Then, let's get this over with quickly. Illya, Miyu. We're counting on you."

"Yes."

"Understood."

After the tumultuous uproar, we had arrived at our destination. A giant cavernous hole in the cave. Apparently, this is where the ritual is to be conducted. Rin planted something that looked like a dry twig into the ground.

The moment it was inserted, a magic circle emerged from the ground where the twig was sticking out. With this, the preparations seemed to be complete. At Rin's signal, Miyu and I began to pour in magical power. We didn't think about the complexities, we simply gave it our all.

That's what Rin told us to do. We didn't know where the blockages might be, so we were told to pour in as much magic power as possible. The details of moderation were to be left to Rin and Luvia. They are the experts after all.

"Magical power filling rate, 60%--75%--90%--100%--110%--115%--"

Rin was counting the filling rate. And then--

"120! Offnen release!"

It seemed to have filled up completely. At the same time as Rin's shout, the light from the magic circle enveloped the surroundings. The ground began to tremble, making me stagger, but nothing really happened, and it all gradually calmed down.

"...Is that all?"

"For now, yes. We need to observe the effects later, but that's for another time."

"Yes, yes, the work is done. Let's go home quickly. This is not a place to linger..."

I felt a little anticlimactic, but if it's over, then that's fine. When everyone breathed a sigh of relief at the words of Rin and Luvia, the ground began to shake again, gradually getting bigger.

"Wait, what is this!?"

"Kyaa!"

Isn't it shaking more than before? When I thought that, a crack appeared under my feet, and a large amount of magical power began to pour out from there. We instinctively jumped back from the spot. Rin, my brother, and I retreated to a nearby spot.

And on the other side were Luvia and Miyu. We were divided with the crack at the center. And then, the situation took a turn.

"Magical power backlash!? No... the output should have been sufficient!"

"This is bad, it's coming!"

Right after Rin and Luvia's shouts, the magical power we had poured in flowed back, destroying the interior of the cave. The destruction reached the ceiling above us, causing a huge rock to fall down on us. Oh, this is going to kill us.

The moment I thought that, I was already moving. It's the third time. My body moves before I can think. What I was aiming for was Rin. There, I knew something that could reverse this situation. I reached out for the thing I had used once before.

"Class Card...Lancer..."

Yes, I knew. Miyu had shown me how to use it. I had already used it once, so I knew I could skip some steps. With the other cards, I would have to recite the summoning spell, but with this one...

"Dream Summoning Install!"

"Wha, Illya!?"

Using the Lancer card in Rin's pocket, I transformed into a heroic spirit. Immediately, I wielded the lance and leapt upwards. The only thing that could blow away all this debris and protect everyone was that.

"Gae Bolg, the Spear that Pierces with Death!"

Without aiming, without reversing causality, I focused only on destructive power and threw the cursed red spear. It erased all the falling debris without a trace, pierced through the thick ceiling, and disappeared into the sky.

The moment I saw that, my body throbbed as something was pulled from within me.

...............…

[Shirou POV]

"Ugh, what the hell..."

Things happened so suddenly, I couldn't understand what was going on. I could recognize that Illya, like that time, had used the card to transform into a Heroic Spirit and threw her spear into the sky. The sheer power of that spear...

Our eyes, dazzled by the intense light, were finally returning to normal. I was thinking about what to do about having Illya's actions witnessed by Tohsaka and the others when I opened my eyes. Everyone stopped moving at the sight.

"Wh...what?"

My voice overlapped with Miyu's, Tohsaka's, and Luvia's. Everyone's gaze was fixed on the same thing. There was...

"Ouch..."

Is there something wrong with my eyes? There was Illya. But, she wasn't alone.

"Huh? What?"

Il...Illya...my sister, has multiplied! There were two Illyas, both with the same bewildered expression as if reflected in a mirror. Yes, two. Plural. There was the white magical girl Illya...

And then, there was the "black Illya," who was wearing a risqué black bodysuit and had her hair tied back.

From this moment on, I had two sisters...

_________________________________________________________________________________________________

Explaination:

Finally, Kuro makes her appearance. As announced, she is a Lancer card.

The Thrown Gaebolg I used this time is being used forcefully with the power of the Lesser Grail. Therefore, I omitted the reversal of causality, which pierces the opponent's heart, and focused only on its power. I think that with the use of Rune Magic, it might be possible to utilize it in this way as well. In terms of power, it would be around Class A or A+ if expressed in ranks.

Since it's the setting of my work, it might be a usage that can't be done in the original. However, Fate/kaleid liner PRISMA☆ILLYA itself is originally a fan-made creation, so there may be differences in the finer details of the settings. Illya also uses a complete projection of Excalibur, after all. So, please refrain from nitpicking on the finer details.