The echo of the blaring alarm slowly faded away. Emiya Shirou, having given up on her panties, adjusted her composure and glanced around the room. The remnants of the intense clash with Archer still lingered in the air, but something caught her attention.

She noticed the damage caused by her fight with Archer was fading away. The room seemed to be fixing itself as if the very structure of Chaldea was healing from the disturbance.

Shirou couldn't help but be impressed. "Chaldea's resilience is quite something," she remarked, her eyes tracing the seamless restoration of the summoning room.

Mash, who had been observing alongside her, nodded. "It's one of Chaldea's unique features. The facility has the ability to repair itself magically, ensuring that even in the midst of battles, we can maintain operations."

"I see...That's actually quite useful—Ah, I forgot!" She swiftly bowed, "I am really sorry for the mess I caused here. I didn't expect things to escalate that quickly."

Ritsuka waved off her apology. "No need to worry, Shirou-chan. It's not the first time, so nothing serious."

"Not the first time?"

Ritsuka chuckled, "Well, not everyone here is on good terms with everyone. There have been a few times when we ended up summoning conflicting servants, and, you know, they don't always get along."

As they exchanged lighthearted banter, they didn't realize that the blaring alarm had drawn the attention of nearby passing.

Without warning, the control room doors slid open with a soft whoosh. The visitor stepped their feet toward the summoning room pulling the gaze of who was inside.

Shirou eyes were the first to widen as she viewed the newcomer.

"Master, we heard the alarm. Is everything—Eh! Another me?"

A soft, childlike voice echoed from a petite girl with fair skin, crimson eyes, and flowing white hair. She wore a charming pink magical girl ensemble—Illyasviel von Einzbern.

"Oh my, and here I was wondering why Archer stormed out looking so furious. Looks like he has another child to babysit. Hehehe~~"

"Wha—What do you mean by that, Kuro?!"

Walking beside Illya, was another girl with the same look and height, as if she was a twin but with a few differences. the young girl had a tanned skin color and white rose-like hair. She was clad in rather something similar to a feminine version of EMIYA's servant clothing—Chloe von Einzbern.

"...She has Illya-san's look but Chloe's hair color. Plus, a purple magical girl outfit," 

Remarked, the last member of the trio. A young girl with black hair tied in low pigtails, golden-brown eyes, and wore a cute blue and black outfit with a white cape and boots—essentially a blue version of Illya's magical girl attire—Miyu Edelfelt.

"So, which class Illya are you? Saber?" said Chloe, already approaching Shirou, walking around her, curiously scanning the girl.

Shirou didn't seem to mind; rather, she didn't seem to notice. The little girl's eyes were fixed on Illya.

"Umm, Is there something wrong mm...Me?"

Shirou remained silent throughout, her mind seemingly not present in the real world.

"Uhh, well I think I have to present you guys to each other"

Sensing the tension in the room starting to rise, Ritsuka decided to intervene. "Everyone, meet Emiya Shirou. She's a new addition to our team, just summoned now"

"E-Emiya..."

"Shirou..."

The three girls completed each other's words in a collective gasp, and the room descended into a deep, contemplative silence.

Shirou met their shocked stares with a calm, almost emotionless expression, before lowering her gaze slowly with a subtly furrowed brow.

"Uh... Why is everyone suddenly silent?" Ritsuka was once again Confused.

"O-Onii-san...Is that really you?"

Both Chole and Miyu remained silent, waiting for an answer as Illya asked...

"mm..." Shirou finally raised her gaze, meeting Illya with a wry smile, "Didn't imagine I would meet you like that again, Illya..."

"O-Onii-chan..."

A quiet, soft voice echoed from the black-tied little girl.

Following the source, Shirou slightly turned her gaze toward Miyu, tilting her head, "Me?" She pointed at herself in confusion.

Miyu fixed her eyes on Shirou for a few seconds before breaking the gaze, lowering her eyes, "N-No, sorry...nothing..."

"...??"

"Wait, hold on!!" Chloe chimed in, "How did you end up in this body?! What the hell is going on!"

Shirou sighed, scratching the back of her head, "Well...It's a long story—"

"Hehehe~~ Let me explain!!"

Shirou's words hung in the air, replaced by a cheerful voice belonging to a certain Mystic Code—a stick with a star-shaped emblem affixed to its peak floating in the air.

"Ruby?!"

"Oh my, Illya-chan, I knew you would look good as a magical girl...And look who's in your hand."

"It seems you got yourself a suited magical girl, Me."

"I sure did. My fellow Me."

The two sticks, Ruby and Ruby from different timelines, exchanged words of pride while the others remained silent, observing the scene.

As Ruby freely floated in the air, a grip suddenly tightened around her. It was Shirou. "I remember I told you not to act without my permission, didn't I?"

"Oh, my? Don't get all upset, Shirou-chan. As a magical girl, you should always be cheerful—OW!! OW!! STOP, STOP, YOU'LL BREAK ME AGAIN!!!"

Not long after, Shirou's simple grip turned into a merciless attempt to bend the stick.

"Umm, Onii-san."

"Hmm?"

Illya's timid voice brought Shirou's attention away from the squirming magical stick. She had an apologetic expression on her face.

"Sorry to interrupt, but...um, how did you end up...in my body?" Illya finally blurted out what had been on her mind, her cheeks turning a faint shade of pink.

Shirou released Ruby with a sigh, allowing the stick to float freely again. "Well, it's a bit complicated," she began, and everyone listened intently.

"This Mystic Code played with my soul somehow. I think she got help from a third party and used your body from a different timeline as a vessel just because she wanted to make me the perfect magical girl, even though I was a man..."

(Another man in a girl's body... Classic.)

Ritsuka mused internally as he observed the intriguing scene from the side. He wished he had a bag of popcorn to enjoy the unfolding drama.

Illya blinked, processing the unusual information, "Ruby?!! That's my brother! What are you thinking about!"

"I know what you're thinking, Illya-chan, but hear me out..." Ruby's voice echoed with a prideful tone, "I was having trouble choosing who has the most potential to become the perfect Magical girl. On one side, we have Illya-chan, who has the best appearance for a good Magical girl. On the other side, we have Shirou-san, who has the suitable and perfect personality and mentality for a magical girl that doesn't fear anything in seeking to save everyone, so..."

Chloe interjected, "So, you thought, why not merge the best of both in one being?"

"Pingo! 100 points for the cute girl over there!" Ruby replied cheerfully.

"That's totally wrong, but why is it making sense?!" Illya said with a perplexed expression.

"Well, it seems we finally answered one of our many mysteries," a new voice emerged, belonging to the representation of beauty, taking the form of one of his best works, Mona Lisa. Da Vinci said, "Since you guys are here, what about giving Shirou-san a tour around the place? Since you seem to know each other."

The group exchanged glances, and as peculiar as the situation was, immediately, both Illya and Chloe grabbed Shirou by the hand, pulling her along, "There's so much to see here, Onii—No, Onee-chan!"

Said Illya with a cheerful, excited smile, followed by Chloe, "Yep!"

Miyu was left behind. Respectfully, she bowed to Ritsuka, Mash, and Da Vinci before following behind the three.

Ritsuka watched her as she exited the door, fading from sight, before blurting out his thoughts, "She looks sadder than usual, right, Mash..."

"Yeah..."

Part 2:

The quartet strolled through the vast and labyrinthine hallways of Chaldea, their footsteps echoing against the sleek, metallic walls. Soft ambient lighting bathed the corridor in a gentle glow.

"So, where to start? The cafeteria? Or maybe the training space... Wah, there are so many things I want to talk about with you, Nee-chan!"

Illya's eyes gleamed with excitement as she bounced on her toes, her energy infectious. Illya, or rather Shirou in Illya's form, offered a small, amused smile.

"Perhaps the cafeteria would be a good start", Shirou replied, her tone carrying the same calm demeanor despite the unusual circumstances.

Illya's eyes sparkled with anticipation. "Great idea! Actually, I missed your cooking, even though the archer in red cooking is also great. But nothing beats Nee-chan's cooking."

"Hm, so he's taking care of the cafeteria as a role here, huh..." Shirou, with a tilted head, mumbled in her mind.

"But it's quite an interesting situation you're in, Nee-chan...", Chole, keeping pace with Illya's excitement, chimed in with a mischievous smile, "Getting stuck in your little sister's body. Aren't you feeling anything?"

"What—" Illya jolted in her place with a red face, "What kind of question is that, Kuro!?"

"Hmm, let's see," Shirou, tapped her chin, surprisingly calm unlike Illya who was stumbling over her words, "there's that difference in height and weight that I am not familiar with yet, a kind of challenge for me in combat. Aside from that, I think I'm doing alright."

"Wah... No reaction at all... Of course, there would be no reaction... It's Nii-san we're talking about here...." Chloe thought, casting a playful smirk at Illya, "Plan B."

"I-L-L-Y-A~~!"

"Wha-" 

Illya jolted again, this time in surprise, as Chloe unexpectedly hugged her. With a mischievous gleam in her eyes, Chloe leaned in, whispering something into Illya's ear, "What about you? How are you feeling about it?"

Illya's face turned an even deeper shade of red, and she squirmed a bit in Chloe's embrace. "K-Kuro, that's enough..."

"Nii-san in your body... There will be a time when he will need to change clothes... take a bath..." Chloe continued to whisper, her mischievous grin widening.

Illya's embarrassment reached new heights. "K-Kuro! Stop it right now!"

Chloe burst into laughter, thoroughly enjoying Illya's discomfort, "Oh, I can't get enough of that face, hahaha!"

"Grrr," Illya growled, her frustration evident. 

Shirou, unfazed by the banter, calmly interjected, "You guys seem to really get along... By the way," her gaze focused on Chloe, "I didn't get to know you yet. I don't know if you guys are already aware of that, but I am not the Shirou you all know. I am from a different timeline. Are you both twin sisters?"

An unexpected weight settled upon the trio as a somber silence replaced the earlier laughter. 

Illya was the first to break it with a nervously forced chuckle, "Well, we've figured it out, but we didn't want to dwell on it... Everyone here has those familiar faces that remind us of the ones we consider close and important but they are not the same people. Just thinking about the idea if you being also one felt disheartening..."

Chloe's playful demeanor shifted, and she exchanged a glance with Illya, the unspoken understanding lingering in the air.

"Ah... S-Sorry..."

"You don't have Nii-san... You're different. Yet, you still radiate the same warmth, carry the same aura, and possess the same personality as the Nii-san we know and love. So, it really doesn't matter if you're not the same one we know. Nii-san is Nii-san..."

"I see..." Shirou's face softened, her right hand Involuntarily raised toward Illya's head

"Eh?!" Illya blinked in surprise.

Shirou patted her head with a soft smile, "Then I will make sure you will not feel the difference, Illya."

"Hehehe~" A genuine, innocent chuckle escaped Illya.

Not long after, Shirou's eyes stole a swift glance at Chloe's face. She was gazing at them as if she was bothered.

With an understated smile, Shirou raised her other hand, "Here." She patted Chloe's head.

"..."

"Your name was Chloe, right? Let's get along from today on."

Chloe didn't respond, avoiding eye contact, though she didn't seem to reject the head pat.

Meanwhile, amidst the whole scene, Miyu was a step behind, silent but attentive. Her gaze occasionally shifted between the three of them, as if she were searching for something beyond the surface.

---