True Sister Wars

[Illya POV]

"Onii-chan!" (miyu)

"Huh?"

"Whaaaaaaat!?" (Illya)

What is she saying! what is she saying! what is she saying! what is she saying! what is she saying! what is she saying! what is she saying! what is she saying! what is she saying!?

"Is that... Sapphire!?"

『Oh, you're right~. That's Sapphire. It seems she's found a pretty good master too, I'm so happy for her. That's definitely a magical girl.』

"I'm sorry I didn't look like a magical girl! But what's with this 'brother' thing? Don't tell me she's Emiya-kun's sister too?"

"..."

What is Rin-san talking about? What is she saying...? I'm the only sister of 'big brother' in this world. So, who is that girl? I ponder for a while... Conclusion. She's my enemy!

"Ruby..."

『Yes, yes, what is it, Illya? Whoa, you look scary, Illya!』

"Whoa, you're right! Illya, calm down a bit! What are you planning to do?"

"What am I going to do? Ahaha, it's obvious, Rin-san... Let's go, Ruby!"

『Oh! This is turning out to be an unexpected and exciting development! Got it, Illya! This is exactly what a magical girl's situation should be like!』

"Wait, Illya! And Ruby! You really need to start behaving!"

Rin-san tries to stop me, but I couldn't stop. I couldn't possibly stop. I held Ruby in my hand and charged towards where my brother was. After all, this is a battle where my position as a sister is at stake!

"Stay away from my Onii-chan!"

"Huh, Illya!?"

"Huh!?"

"Go, Illya! As the real sister, you absolutely cannot lose this fight!"

『Sister Ruby!?』

I strike at the girl hugging my brother with Ruby. The mysterious girl, no, the "fake sister" holds a wand similar to Ruby, and she blocked my attack. She even pushed my brother away. She seems quite strong.

When the fake sister blocked my attack, she made a bitter face. It looked as if she regretted something. But I didn't care about that. The problem was that this fake sister was trying to take my brother away from me.

"Wa, wait, let's talk..."

"I don't want to talk! I absolutely won't hand my brother over! My brother is mine and mine alone! You fake sister!"

"Sapphire..."

『Miyu-sama?』

"First, let's knock her down."

"Miyu!?"

『This, this is becoming an even more interesting situation!』

『Sister, please wait!』

I knew it! I was certain. This fake sister is my enemy. Any girl's intuition would tell her that. I don't care who this girl is or why she's here. I have absolutely no interest in that. I glare at the fake sister.

The fake sister glares back at me. That gaze communicates her feelings more eloquently than anything. She feels the same way about my brother as I do. There are things that can be communicated just by making eye contact. I think my feelings got through to the fake sister.

"Huh!?"

Her glare sharpens. I too, intensify my gaze. We are at close range, glaring at each other in a showdown. The sound of tension echoes and the air around us trembles. It is an absolutely must-win battle.

Yes, this is indeed the "Real Sister War"!

"Yaah!"

"Huh!"

"There! 'Cannon Fire'!"

When I put force into it, the fake sister steps back. I seize the opportunity and fire a full-power cannon. The fake sister flinches for a moment, but quickly fires back a cannon shot of similar magnitude. It seems her wand is the same as Ruby.

"I'm not a fake sister...!"

"You are a fake sister! I am the only sister of my brother in the world! 'Rapid Fire'!" (Illya)

"Huh!? But that's..."

『That's the spirit, Illya! You're shining the most right now! More!』

『What are you saying, Sister!? Miyu, please stop too! Isn't this the same as what Rin and the others are doing!?』

『Sapphire, what are you saying? This is a holy war of a maiden in love! It's completely different from the ugly fights of those old women!』

Ruby and the fake sister's wand are saying something, but it doesn't matter! I continue to rapidly fire, trying to defeat this fake sister as soon as possible. The fake sister continues to fire rapidly as well, cancelling out my attacks. No, this won't end if it continues like this.

We both were thinking about how to break this balance. And we arrived at the same conclusion, which was...

"Ruby!"

"Sapphire!"

We screamed simultaneously. We decided to unleash our full-powered cannon shots, raising our magical power to the limit...

......…

[Miyu POV]

I muttered to myself, "Oops." I had made a rule for myself when I came to this world. It was not to bring the relationships from my original world into this one. Even if I knew someone, they were strangers in this world.

Therefore, I intended to start from scratch in this world. I had decided not to break that rule no matter who the person was. But there was one person I couldn't resist. Only one.

I never expected to meet that person so early on, and especially not in a place like this. The most important person to me. The reason I couldn't resist was that I wasn't mentally prepared. It was the same person as my beloved older brother.

Moreover, that person exuded a similar aura as my brother. To the extent that I lost myself and fell into an illusion. They looked at me with the same face, the same atmosphere as my brother, and spoke with the same voice.

I thought I understood it logically. It was obvious, and I could have predicted it. This person in this world is not my brother. We may share the same existence, but they don't know anything about me. I thought I understood it in my head, logically.

But when they actually appeared before me, all reason vanished. My brother was looking at me. He was speaking to me. The brother I had given up on ever seeing again! In that moment, all sense of reason was lost.

Tears overflowed uncontrollably, and I clung to that person. My brother, who had fought for me with everything he had and given me a future. Someone who could be called the same existence as him. With a blank mind, I surrendered myself to that warmth...

"...'Miyu'...?"

"!?"

...Huh? I regained my senses at the voice that came from above. What did this person just say? Did they say 'Miyu'? How did this person know my name? There was no way people in this world should know my name...

Shirou in this world, who gently strokes my surprised face even though he seems puzzled. This can't be possible. It must be some sort of mistake. The calm part of me says so in my head, but I can't hold back any longer.

"Onii-chan..."

"Stay away from my brother!"

"Huh, Illya!?"

"Huh!?"

As I was about to hug him again, overwhelmed with emotion, an angry voice came from the side. On instinct, I pushed Shirou away and distanced him from the scene. There was a silver-haired girl swinging her Kaleidostick at me.

I also blocked her blow with Sapphire. We were in a standoff. And at close range, a girl glaring at me. "My" brother. From those words, I could guess that she was probably the sister of Shirou in this world.

Damn it. This is completely my fault. Guilt and self-loathing overwhelmed me. The Shirou in this world is not my brother. I was reminded of that fact. He is this girl's brother. A sharp pain stabbed my chest.

"W-wait, let's talk..."

So I tried to apologize. I tried to talk. But she wasn't willing to listen. She screamed in anger. A forbidden word.

"I don't want to talk! I won't give up my brother! My brother is only my brother! You fake sister!"

"..."

At those words, something inside me snapped. I heard a small sound in my head. The word "fake sister" stole my calmness.

"...Sapphire..."

『Miyu-sama?』

"Let's crush her first."

『Miyu-sama!?』

And so, we ended up clashing over our feelings for our respective brothers.

Yes, this was indeed a "True Sister Battle."

"I'm not a fake sister...!"

"You are a fake sister! The only sister in the world for my brother is me! Rapid Fire!"

"Huh!? That is...but!"

As we clashed, I realized that she, too, was harboring the same feelings for our brother. I wonder if she's not related by blood either. We express our feelings to each other while battling. Neither of us back down.

Even so, the word "fake sister" rubs my nerves the wrong way. Sure, my brother and I aren't real siblings. But in the end, he told me. He's my brother, so it's only natural to protect his sister.

I know she doesn't mean it that way. But even so, I can't let her deny me. I fully understand that she is right. But it doesn't matter. This isn't about logic anymore.

"Ruby!"

"Sapphire!"

That's why I can't afford to lose to her. Emotions beyond reason rob me of my calm judgment. We both push our magical powers to the limit in order to release a full-power cannon shot.

......…

[Shirou POV]

"..."

Held by the mysterious girl, I looked down at her in confusion. I recognized her, but it was from a dream of mine. If I shared this with anyone, they would probably laugh it off as nonsense.

But I couldn't write it off as just a dream. Because my heart was screaming. Having been Illya's brother for many years, I could understand this girl's sorrow. She was calling for help right now.

And... I felt as though this girl was like a sister to me, probably because of that dream. As I pondered this, a sharp pain ran through my head again. And another vision surfaced. This girl, lying at the center of a magic circle, and me, watching her.

"Miyu... I entrust my sister to you..." (Shirou - Miyu World)

"Leave it to me." (Shirou - Illya World)

"...'Miyu'...?" (Shirou)

Yes, this girl's name was Miyu. The other me told me so. As I murmured her name, the girl looked up in surprise. Her expression seemed to say that she couldn't believe it. Her widened eyes were brimming with tears.

Confused, I was stroking Miyu's head, just as I always do with Illya. My body moved on its own. Miyu seemed stunned for a while, but then she scrunched up her face and tried to hug me again.

"Stay away from my brother!"

However, suddenly from the side, I heard Illya's voice, filled with anger. In an instant, Miyu pushed me away. The next moment, Illya and Miyu's magic sticks collided. With the strength of the enhanced Miyu, I was blown far away.

"Argh! Stop it, Illya!"

I was blown away, landing near Tohsaka. Not only was Tohsaka there, but Luvia as well. As expected when I saw Tohsaka, it seemed that Luvia too was on the side of the extraordinary. At the same time, I realized that Miyu was Luvia's accomplice.

"Wait a minute, Tohsaka Rin! What is going on here? Attacking my associate's child all of a sudden! It's true what they say, pets resemble their owners. She's behaving just like a monkey, just like you!"

"Shut up! Who are you calling a monkey!"

"Hey, Luvia, don't talk about my sister like that. It's true that Illya was in the wrong this time, but she's actually a very good girl."

"Oh, really? Emiya Shirou? That girl is your sister? I apologize for my rudeness. ...Wait, why are you here?! And what's with your appearance?! Explain, Tohsaka Rin!" (Luvia)

"I don't know either! Emiya-kun! You need to explain this to me later!" (Rin)

"Alright, I understand. But there are things I want you to explain to me too, like about my sister. But right now, we need to deal with Illya and the others first, right?"

"Ugh, I guess you're right..."

"Well, in that case, don't worry."

"Huh?"

While we were each voicing our questions, we concluded that first and foremost, we needed to deal with Illya and the others. Then Luvia told us not to worry. What did she mean by that?

"Miyu is such a talent that I personally entrusted her with the Kaleidostick. She is always calm and collected, highly intelligent, and a wonderful girl full of compassion. The saying 'like owner, like pet' is not always negative. Ohohoho!"

"...I don't like the way you put it, but if that's the case, let's see how it goes."

"Ohohoho! Watch closely, Tohsaka Rin! If it's Miyu, she'll surely resolve the situation calmly..."

Well, if that's the case, it should be fine. I decided to trust Luvia's words and watch over the situation. But...

"Wa, wait, let's talk for a..."

"I don't want to talk! I will never give up my brother! My brother is my brother only! You fake sister!"

"...Sapphire..."

『Miyu-sama?』

"Let's smash her first." (Miyu)

『Miyu-sama!?』

"Mi, Miyu!?"

"Hey! This is not good at all! She really is just like her owner! Oh my, my words just came back to bite me! This is so embarrassing!"

"What!? But the child you brought started attacking Miyu first! You're forgetting that!"

"How do you know such a Japanese phrase!"

"Distance education!"

"Calm down! Don't you two start fighting too!"

This is a mess. Illya's fight? It's escalating, and even Tohsaka and the others have begun a real brawl. What should I do? I can't attack Illya and the others. And then, in my confusion, a bad omen echoed in my ears...

"Hey, Tohsaka, Luvia! Didn't you hear a sound like something breaking? It was a really ominous sound!"

"Huh!? You don't mean!?"

"This is bad, Tohsaka Rin! The Mirror World is collapsing! It seems that it can't be maintained after the corrupted Servant was defeated!"

"Eek!? I see, that's what's happening! If we don't get out quickly, we'll be caught in the collapse of space! But to get out of the Mirror World, we need their Kaleidosticks!"

"Is that a bad thing!?"

"It's super bad! We'll be left behind forever in the gap of space and time!"

"That is bad!"

"That's what I've been saying!"

This was worse than I thought! We looked towards Illya and the others. They were glaring at each other, each creating an enormous ball of light. Seeing this, we all turned pale. Hey, wait a minute, that is!

"Stop it, you two! If you let that thing loose, this space might really disappear! Illya!"

"Miyu! Stop it!"

"Argh! Illya! Miyu!"

We shouted desperately. But our cries were in vain, and Illya and the others released the massive light bullets at each other.

It's over... In my heart, I muttered. Our field of view was filled with white.