Pleased to meet you, I am lil'chrome-chan, though my fellow author friends prefer to call me "Chrome". This is my first time writing a fic for this fandom so please forgive me if there are errors. You are free to point out every fact I mistook, because I am no expert in science (in fact, my academic scores for science subjects are the worst compared to all).

As for the title, I assume you are all familiar with the term "Least Squares", aren't you? I am not sure since I don't study math in English but I google searched it beforehand so I guess this is good enough. Least squares is another method to solve statistical problems aside from tree diagram (there are other methods besides these two) and is a superior one, I guess. So in short, I chose Least Squares to name the new super computer simply because it sounds more likely to be a computer name than the other methods. Not expecting much of me, huh?

On to the ESPer power of our beloved Mikoto and Kuroko: I have little to no knowledge regarding the matter and if I were to make mistakes, PLEASE point them out, it will be a big help! In addition, my knowledge is limited to TAKNR because I only watched a bit of Index. On a completely unrelated note, if there is someone out there who's possesses wide range of vocabularies and great grammar, I am more than happy if you would become my beta reader.

Disclaimer: I do not own both TAKNR and TAMNI…

[The White Siblings and the Least Squares]

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by: lil'chrome-chan

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Chapter 1: Electromaster

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SUMMARY:

Atop of Judgment work and cleaning up after the mess left by her Onee-sama, Shirai Kuroko now faces another form of calamity, namely the arrival of a powerful Electromaster from outside the Academy City and the rumors of a brand-new Super Computer reaching completion, which, introduces Kuroko to a new level of frustration. Again, the Academy City is up to something—and she is caught in the middle of the mess.

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Kuroko sighed for the umpteenth time today. Massaging the back of her neck, she encouraged herself to finish one more document before going home. After all, she was writing an apology letter for Onee-sama's sake. If she didn't finish this Onee-sama would have to face the higher-ups' wrath. Indeed, this was not the first time her Onee-sama upset the public facility when going rampage. Kuroko assumed that the higher-ups would get fed up soon enough.

Again, she let out a weary sigh.

"You should head home soon, Shirai-san, it's already dark outside," Uiharu said as she handed Kuroko a cup of hot coffee while glancing outside the window.

Kuroko politely accepted the cup as a mean to warm herself up a bit, and she sighed in content. "Well," she spoke up, taking a sip of the hot coffee "if only Onee-sama would watch her actions even for a little bit, it would save me a lot of time for myself."

Chuckling nervously, Uiharu responded "Mikoto-san isn't Mikoto-san without causing trouble when trying to end one."

Lips forming a dangerous smirk, Kuroko's eyes glinted, "And that side of Onee-sama is again very adorable," she nodded to herself.

Uiharu chuckled nervously again, not sure whether the Teleporter wanted her Onee-sama to change or to remain causing trouble like she always did. Either way, it seemed everything the Electromaster did only aroused the Teleporter more.

Kuroko ran like there was no tomorrow. She would go past the curfew in another minute. Having her neck twisted backward by the Dorm Mother didn't seem very enchanting at this moment.

Oh, darn.

She decided to pick the easiest route: teleporting. This way no one would know she was late. Almost automatically, her brain counted the coordinates of her destination when she was within the range. With a single jump, she was now inside her dormitory room.

"…Kuroko?"

She turned around only to see her Onee-sama, with hair damp and Gekota pajamas worn. The older girl was drying her hair with a pink towel when she approached her junior. It was obvious she had just finished her bath.

"Tadaima, Onee-sama!" she jumped and buried her face in the Electromaster's chest.

"Geez, you didn't say you're going to be late. Be grateful that I covered for you when the Dorm Mother did her patrol just now. Where were you, Judgment work again?" she asked.

It was a shame she had to let go of her Onee-sama when the older girl unusually didn't push her away when she hugged her, however Kuroko couldn't help but sense something odd from her Onee-sama's sentence.

She tilted her head, "I was writing an apology letter in your stead as usual, though, Onee-sama."

Normally Onee-sama should know that whenever she caused trouble, Kuroko would be home later than usual. Could it be she had forgotten?

"Eh?" the Electromaster looked puzzled, "What did I even do?"

Kuroko raised a brow, "Um… You upset the traffic lights as usual?"

Mikoto blinked before she scowled, "I didn't do anything like that! I mean, I was hanging out with Saten-san the whole day. Anyway, is it even my fault those traffic lights are so sensitive?"

Alright, this respond was enough proof that her Onee-sama wasn't behind today's trouble, that, she respected. However the report did say that it was an Electromaster's doing that caused the damage. The report mentioned that a fight broke out in the alleys near the damaged traffic lights. It was all based on the witness' testimony. Or was it a false report? No, it was very unlikely.

D-d-don't tell me there is another Electromaster going rampage after seeing Onee-sama? If so, then Onee-sama is setting bad examples for the other Electromasters! I must not let this go!

"Onee-sama!"

"Y-yeah?"

"You are now banned from using your power as you please!" Kuroko warned as she put her hands on her hips in a scolding pose.

"You've said those lines a hundred times already and you know I won't listen."

"If your actions cause further inconvenience toward us Judgment I will have to arrest you, Onee-sama. You know I do not wish to do that." Visible sadness was written all over the junior's face as she looked down.

Mikoto scowled and scratched the back of her neck. She didn't know how to reply to that line.

"W-well, maybe I'll try to hold back every now and then!" she stammered as she folded her arms and turned away.

Kuroko clasped her hands together and smiled, "Splendid!"

Mikoto sighed.

That night, Kuroko saw a dream, a very nostalgic one. It was as though pieces of memories from her past coming to her bit by bit like a puzzle. One was of her lone self sitting under an oak tree at the backyard of her house; the other of herself scolding a much older boy, much like how she did for her Onee-sama; and many others.

It was as though somebody was calling for her.

The next thing she saw was a much taller boy smiling at her, even though she couldn't make out his face, placing his palm on her chubby cheek and spoke with a gentle voice,

"I love you, Kuroko…"

In the morning, she awoke with a start. Her eyes shot open and beads of sweat formed all over her body, making her feel somewhat uneasy. Sensation of her skin crawling in the morning right after she woke up wasn't at all pleasant. Rather than surprise, it was more to disgust. Recalling the last line in her dream, she shuddered, her face turned blue and she had to put her palm on her mouth to prevent herself from throwing up. She had never wanted to hear anyone say that line aside from her Onee-sama, let alone a male. It was plain disgusting.

I must be getting tired due to Judgment work…

After charging her "Onee-sama's morning sleeping face" parameter, she let out a sigh of content before she slipped off her warm blanket and proceeded to brush her teeth. In the middle of her activity, her phone suddenly went off. Retrieving the small phone from the pocket of her pajamas, she immediately choked after reading the content of a certain message.

"…and that's where I heard the rumors!" Saten finished with a satisfied look.

Stirring her melon soda mindlessly, Mikoto then smiled nervously at the person sitting across her, "Well… how do I say this… isn't it just a rumor?" she muttered.

"Tsk-tsk-tsk," Saten made a motion with her index finger as though saying that Mikoto was wrong. "Unlike my previous searches, this one isn't a rumor!", and that was when she re-explained the whole rumor by adding the supporting facts and even some information regarding the confirmation from various parties.

This morning Saten just asked Mikoto out again and after Kuroko left in a rush, Mikoto had no choice but to accompany the black-haired girl. Well, she'd rather hang out with someone than reading manga while standing at the convenience store. They met up at Joseph's and that was when all of this began.

At first, Mikoto was shocked beyond belief when Saten brought up the news about a new super computer being built. The first thing in her mind was the fear that those inhumane experiments might continue again and she definitely didn't want to imagine that. It had been a peaceful year she just couldn't bear to see another nightmare. They had announced the current condition of the Tree Diagram a month ago and had promised the citizen that the new one would be crafted soon but she didn't expect it to be this soon. Building a super computer was not the same as building lego.

"The name is Least Squares, you see! Sounds like it's going to be even more accurate than the Tree Diagram! Please read this article, Mikoto-san!" Saten sounded overly-excited as she showed the other girl her phone screen—the website showing the article she had mentioned.

Mikoto leaned in just to steal a glance but the article grabbed her full attention immediately. Snatching the phone from Saten's grip, much to the latter's surprise, Mikoto fast-read the contents of the article. Indeed, there were some official documents and interview results included to support the statement. Crap, this wasn't funny anymore.

"How are they going to built it so soon? I mean, to built a new super computer we need—"

"I know, right? But if it's already confirmed it means there's some really shady and powerful people backing us up? Isn't that a good thing? At last I can dry out my laundry without being worried if the weather forecast might be wrong!"

"Is that really the case?" Mikoto sweatdropped.

Well, getting depressed not wouldn't solve a thing—actually, it's not like she could stop them from building the new super computer. Maybe by then, the result would be different. Maybe by then she wouldn't have to see her clones suffered. She had to think positive.

She pumped her fists.

A weird feeling rose in her chest by then. She touched it and felt as though she would lose something important if she let this happen. She shook her head, trying to convince herself that everything was just her. She was just being paranoid after everything.

Yeah, she was just being para—

"Hey, isn't that Shirai-san just now?" Saten said, pointing at the window beside them.

Mikoto knew. She saw her clearly just now. Even though she only appeared there for a moment—she was probably teleporting—Mikoto could see it clearly. That girl was probably chasing some thug again, but that face she was making, so desperate and scared, this person she was chasing wasn't your everyday thug.

Mikoto rose from her seat.

"I'm gonna check on Kuroko for a bit!"

"Eh? But…"

And the electromaster was already nowhere within sight.

Letting out a sigh, Saten decided to just continue browsing the internet by herself. Just when she was scrolling down the same page she was seeing with Mikoto just now, a certain article grabbed her attention.

"…the White Siblings?"

Mikoto had run toward where Kuroko seemed to be heading to but still couldn't find the girl. Unease filled her heart with every step she took. Crap, she was really being paranoid. It was not like it was confirmed that Kuroko was in trouble. Shaking her head, she told herself to think straight and calm down. Slowing her track, she decided to take her time to think straight before taking any decision. Her mind went back to last night. Kuroko had scolded her again and it made her realize that her rushed decision was what caused every mess she had done. This time she would think rational.

As she was trying to run her mind, her ears caught small sounds—white noise along with occasional person's voice. She looked around for the source of the voice and spotted something familiar. She bowed down and picked up what seemed to be a small device Kuroko always used to communicate with Uiharu during a chase. If this device was left here it meant either Kuroko dropped it, which was very unlikely, or she threw it away herself.

Mikoto put the device in her ear and listened to the blurry voice of Uiharu.

"…Shi…san! …rai…an!" came an urgent voice from the other side.

The device must be broken after the impact it received when hitting the ground. Mikoto figured she might be able to fix it by giving small electricity to fix the circuit and so she did. After the attempt, Uiharu's voice was now much clearer.

"Shirai-san! Can you hear me, Shirai-san?!"

"Uiharu-san? What's wrong?"

"…Mikoto-san?"

"Yeah it's me—"

"Mikoto-san! Please help Shirai-san! She was chasing an unidentified person that's assumed to not be a citizen of this town. That person was the one who caused the facility malfunction yesterday and—"

Now that she recalled, Kuroko did mention something about that.

"—he's an Electromaster!"

Mikoto held her breath. No, there were numerous of Electromasters in the town and this one might just be your everyday Electromaster. But what was this feeling that bothered her so much since earlier? She squeezed her chest and tried to cease her nervousness.

If this Electromaster was really dangerous, she needed to come to Kuroko's aid as soon as possible.

"—and then Shirai-san suddenly threw the communication device away. I have no idea why she did that but—"

"Uiharu-san, inform me about Kuroko's current location!"

"E-eh… u-understood… Th-the Electromaster deactivated the surveillance cameras around them but they were last seen at area G. Please hurry, Mikoto-san, this Electromaster is powerful! Shirai-san wouldn't stand a chance against him!" Uiharu informed urgently.

"Got it," and Mikoto dashed off to area G. It wasn't that far from here. If she were to use her electricity it would be much faster, but in a wide road like this it would only slow her down. Not to mention she might electrify some innocent citizens or cause facility malfuction—something she's trying to avoid doing. Clicking her tongue, she increased her speed, just how fast her feet would take her.

Detours, sharp turns, and even high jumps were done as long as she could arrive faster.

"I'm here, Uiharu. Where's Kuroko's current location?"

"The last deactivated cameras were in a certain alley. Please proceed forward and turn right at my signal!"

"Roger!"

When Mikoto entered the alley, however, she could see blue sparks flying everywhere. Her eyes widened. The range of the electricity was ridiculously wide, maybe even roughly the same level as hers if compared. Shaking off the suspicions, Mikoto tried to focus on task at hand. Her main priority right now was to save her junior from whatever trouble she was in.

"It is a shame for you but I am immune to electricity!" Kuroko's voice could be heard from the other alley. Mikoto sighed in relief. At least it proved that her junior was safe and sound.

"Kyaaa!" the screamed made the Electromaster's heart jumped.

"Nobody will come even if you scream like that," came a foreign voice that sounded much like a young male. And the voice was dangerous.

Running, Mikoto made a turn to enter the alley of where Kuroko was fighting in, "Kuroko!"

However the sight before her made her gut twisted. Seeing her junior in a vulnerable position, caged under the figure of a young man enraged her for many reasons. Clutching her fists, she let her nails dug into her palm and blue sparks began to appear around her, preparing to strike the enemy.

A gasp, "Onee-sama!?"

"…Onee-sama?" the stranger tilted his head and trailed his gaze to where Kuroko was looking. When his gaze landed on the zappy girl, his lips formed a smirk, "Ah… Is this the famous Railgun I've been hearing about?" he asked playfully as he got up from the ground and helped Kuroko up as well, only to have his hand slapped away by the smaller girl.

The guy chuckled, "Your electricity won't work on me. I mean, despite everything I'm also an Electromaster, you know?"

Blinking, Mikoto suddenly thought that the situation wasn't like how she assumed it to be.

"Onee-sama, why are you even here?" Kuroko inquired as she sprinted toward the older girl. "Oh boy, you're all dirty," she said as she combed Mikoto's hair with her fingers.

"E-eh? Um… I was looking for you. Uiharu-san said that you're chasing some dangerous criminal or something."

"Yes, I was, but I had everything under control. I mean, you don't need to go all the way to look for me or anything…" Kuroko looked sheepish all of a sudden as she played with the tip of her pigtail.

"No, you didn't. Guess what I saw when I came looking for you?" Mikoto glared.

Kuroko blinked. It didn't take long for her to know what Mikoto was referring to. "Eh? Erm… That's…" as she desperately tried to think of a favorable explanation, the young man whose presence had been ignored for a while butt into the conversation.

"Don't blame everything on Kuroko, Railgun. This is partly my fault," he said wisely.

"…Kuroko?" Mikoto raised a brow at how friendly this guy called Kuroko to the point of using her given name. The two of them only met for the first time when Kuroko began chasing him, right?

Kuroko gasped when she saw the communication device Mikoto was using.

"Ah, I haven't properly introduced myself, have I?" the guy smiled. "My name is—akh!"

Almost immediately, Kuroko elbowed his stomach and snatched the communication device from Mikoto's ear before stomping on it until it's completely beyond reparation.

"Ku-Kuroko!?" Mikoto gasped at her junior's sudden action.

"Worry not, Onee-sama, I will properly pay for the damage," Kuroko said monotonously.

"That's not the case!"

"Now, now, don't fight, girls."

"We're not fighting!" Mikoto snapped. "Who are you anyway?" she glared.

At that question, Kuroko visibly tensed.

Mikoto noticed that the younger girl had been trying to prevent the guy from introducing himself. And she even broke the communication device, presumably to avoid Uiharu listening to their conversation. Could it be he was belonged to a very powerful and dangerous organization? But why would Kuroko be aware of that fact when Uiharu and presumably the other Judgment members, didn't?

"Right, let me introduce myself again."

Mikoto gulped, preparing herself for the worst.

"My name is Shirai Ginsei—"

Mikoto held her breath as her eyes widened while Kuroko tried to avoid looking at any of them.

"—Kuroko's older brother."

"…eh?"

Mikoto blinked and Kuroko hid her face behind her hands as though to save her from the humiliation.

"Nice to meet you," Ginsei smiled.

"EEEHHH!?"

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To be continued

This is only an experimental fic I wrote for fun. If this fic is welcomed by the readers in this fandom, I will post more chapters, but if it's not good enough I'll just continue writing in for fun in my laptop :P

Please tell me your opinion regarding this story… and please be gentle! (I'm just an innocent MikoKuro fan :3)