A Certain Magical Index: The Primal Spirit Descends to My Side

The afternoon sun scorched the outdoor swimming pool area of ​​Tokiwadai Junior High School. The pool water, which was crystal clear yesterday, was drained into the sewers for cleaning the pool. What should have been a cool job was now made even hotter by the sunlight reflecting off the tiles.

"Seriously... why do I have to do this...?" Misaka Mikoto scrubbed the foam on the floor with a stiff, long-handled brush. "It's a bit much, really... but this punishment... cleaning this ridiculously large swimming pool! It's just asking the impossible!"

Misaka Mikoto's voice echoed in the empty swimming pool. Since it was Sunday, the swimming club members who usually played there were not there.

"Sigh..." Misaka Mikoto stopped what she was doing, slumped over her desk like a student, her hands folded over the brush handle. "I've been cleaning since this morning... and I haven't even finished a third of it! I don't even know if I can finish today..."

Shirai Kuroko gripped a long-handled brush, vigorously scrubbing the floor while pouring detergent over it. Her brown twin tails, soaked with sweat, hung limply. Her white shirt, drenched in sweat, clung to her body, the sticky, heavy, and slippery feel making her extremely uncomfortable, but she resisted the urge to change.

If you ask why, it's because...

"Hehehe..." Shirai Kuroko pretended to be working, but was actually using the act of working to cover up her sneaking glances at Misaka Mikoto. "How lucky... to be able to enjoy some alone time with my sister, who's soaking in sweat, at the pool~"

The intense heat and exhaustion began to truly erode their strength. Misaka Mikoto leaned against the poolside railing, panting heavily and wiping away sweat. Kuroko's eyes suddenly lit up at the sight. This was truly a once-in-a-lifetime opportunity to avenge their morning's humiliation!

"Big sister~ Are you thirsty? It's essential to stay hydrated while working under the scorching sun~ Here's a special sports drink!" She pulled an ordinary purple water bottle from her small bag, which looked perfectly normal.

"No…"

Why?

"In there..." Misaka Mikoto stopped washing the towel in her hand, her icy gaze piercing Shirai Kuroko: "You didn't put those so-called 'computer parts' in there, did you?"

Shirai Kuroko was sweating profusely, holding the cup as if it were a hot potato. She couldn't throw it away, because doing so would prove she'd actually put it in. And that would mean losing her older sister's trust!

"Just as I expected..."

Seeing that Shirai Kuroko remained silent, Misaka Mikoto was now certain of her guess, and her gaze towards Shirai Kuroko became even more distant.

"Shirai-kun?"

Just as the two were having their "everyday" conversation, soft footsteps came from the pool entrance. Two girls wearing Tokiwa-style swimsuits and white shirts walked in, looking slightly surprised at the scene by the pool.

"It really is Shirai-san... What are you doing here?" One of the girls, with long, flowing hair and a gentle demeanor, asked.

"Ah, it's Awafuki-kun and Wannai-kun." Shirai Kuroko turned around, answering her classmate's question with a sigh. "As you can see... they're cleaning the pool..."

"But why?"

"Even in early summer, it's hard to escape the coldness of human nature..." Shirai Kuroko sighed deeply. She wouldn't let go of an opportunity to mock the dorm supervisor behind her back. "Speaking of which, what are you doing here? It's Sunday, the swimming club isn't open..."

"We are members of the swimming team..."

"Kuroko's classmate? So that means..."

Misaka Mikoto watched Shirai Kuroko talking to two classmates, her eyes involuntarily drawn to the size of their breasts. Then she looked at her own chest; she couldn't see her toes, and she could even see her thighs.

"Is she younger than me...?"

"Big sister~"

Shirai Kuroko's voice interrupted Misaka Mikoto's thoughts. Misaka Mikoto, who was thinking about impolite things, quickly responded and then took a few steps forward to cover up her embarrassment.

"These two are my classmates, Wan Nei Juanbao and Pao Fu Wanbin."

As Shirai Kuroko introduced them, Misaka Mikoto greeted them with a smile. "Hello..."

Just as Shirai Kuroko finished introducing her classmates and was about to introduce Misaka Mikoto, Wanai Kinuho interrupted her. "Um... excuse my intrusion, but are you Misaka-senpai?"

"Huh? It's me..."

"I knew it!" Kinuho Wannai quickly jumped off the stage, but almost slipped on the detergent that Kuroko Shirai had spilled. Luckily, Kuroko Shirai saved her in time.

"Do you remember? When I was surrounded by delinquents in Chida, you were the one who helped me out."

"Ah... there's that too..."

"Thank you so much for what happened that day..." Wannai Kinu bowed deeply, and Awafuki Manbin, standing beside her, also bowed. "I've long admired your name; it's truly an honor to see you in person!"

"As expected of my older sister~ She's punishing criminals even when I don't know it," Shirai Kuroko thought to herself, preparing to join the conversation. However, she found the three of them chatting so comfortably that she couldn't find a topic to start.

Watching the three of them chatter more and more happily, Shirai Kuroko suddenly had a feeling of familiarity. This was... déjà vu!

This morning, my older sister was chatting enthusiastically with Saten and Haru, leaving me out of the conversation. That's why she deliberately interrupted their chat and ended up getting a one-day swimming pool cleaning voucher.

Shirai Kuroko shook her head, banishing these thoughts from her mind. She must be overthinking it; it was just that what happened this morning had made her too sensitive… How could her older sister deliberately distance herself from Kuroko!

Then she saw Kinuho Wannai hand her drink to Misaka Mikoto. Haha, that's child's play, her older sister would definitely refuse... But Misaka Mikoto just took the drink and drank it straight from the bottle without even looking at it!

Huh? What's with this drastic difference in attitude? Come to think of it... I was ignored so many times before. Even when I put on my favorite pajamas and tried to seduce my older sister, she ignored me. When I tried to win her back by only wearing a bath towel into her bathroom, I was thrown out. When I tried to deepen our relationship by wearing a bath towel and crawling into her bed, I was hit with a German-style back throw.

Could it be that my older sister is deliberately distancing herself from me? Don't let me down, Kuroko! Cheer up! If you've lost your confidence, regain it; if you feel insecure, drive it away! That's right, as long as I use my advantages, as long as I have the ability to teleport, I'll have countless opportunities to lend my older sister a hand…

Shirai Kuroko stood up, preparing to use her expertise to help Misaka Mikoto and regain her trust. But as soon as she turned around, she saw Wanai Kinuyasu manipulating the water flow to quickly wash the tiles, much faster than when they had been scrubbing them bit by bit with brushes.

Even Misaka Mikoto exclaimed in praise, "Wow! Amazing! It's become clean so quickly!"

"My ability is to control water flow. Although I have to submit inspection reports to the teacher regularly, can I help out after that?" Wannai Kinuho said with a gentle smile as she manipulated the rapidly spinning water on the ground.

"But..." Misaka Mikoto was a little embarrassed and was about to refuse, but was stopped by a single sentence from Wanai Kinuho.

"This is just a small token of my gratitude for your help that day..."

"Thank you! You've been a huge help!" Misaka Mikoto exclaimed with a smile, showering her with praise. "You're really amazing!" "This made things so easy for me!"

The laughter of the three echoed in the empty pool, each time forcefully silencing Shirai Kuroko's words, shattering the unspoken words and swallowing them back down her throat.

"Well then... see you later..."

"The drinks are here, please help yourself..."

After they finished speaking, the two bowed again and left. Only the creaking sound of the iron gate closing remained. Misaka Mikoto smiled and waved goodbye.

"Oh my...he seems like such a good kid...Kuroko..."

"That's true."

"This is a huge help; now it might not even take ten minutes..."

"That's true."

"Hurry up and get this done, I really want to get some ice cream on the way back..."

"That's true."

Which Chinese dynasty emerged in the tenth century?

"That's true."

"What's wrong? You seem a bit listless..."

"It's nothing...please don't mind..." Shirai Kuroko continued scrubbing the floor tiles. "Anyway, I'm just a useless person who can't even clean properly..."

"Um... if something's on your mind..."

"No need!" Shirai Kuroko suddenly shouted, her voice then trembling violently. "It's all my fault for being completely unworthy of Onee-sama... I only cause trouble and am utterly useless..."

"I have absolutely no right to stay by my sister's side..." After saying this, Shirai Kuroko could no longer hold back her emotions and burst into tears.

"I wonder if Misaka-senpai gave that to Shirai-kun...?"

Inside a street-side coffee shop, Uiharu Shiori was enjoying the air conditioning, holding a cup of milk tea. Beside her, Saten Ruiko was biting her straw and looking over.

"Since we're going to give it to them anyway, I really want to see that moment with my own eyes..." Saten Ruiko leaned on the table, resting her chin on her left hand. "It's such a rare opportunity to go shopping together..."

"I'm really interested in Shirai-san's reaction. Look at her interest in lingerie..."

"That's true... I never expected her to be that kind of interested..." Saten Ruiko held the milk tea up in the air and waved it at Hina Haru. "But... it's the thought that counts..."

Haru Shiori responded with a smile, touching Saten's milk tea to her own.

"That's true..."

"I said...Kuroko?" Misaka Mikoto said with a smile, seeing that Shirai Kuroko had almost finished crying. "Do you remember what happened a month ago today?"

"One month ago today?"

"That's right... the very night you insisted on moving into my dorm... you got caught red-handed by the dorm supervisor and gave her a good scolding, right?" Misaka Mikoto continued, seeing that Shirai Kuroko had stopped sobbing, "And so, the very next day... we were punished by having to clean the cafeteria lobby..."

Listening to Misaka Mikoto's words, Shirai Kuroko recalled. That day, she was diligently cleaning. Misaka Mikoto, who had been punished because of her, sat on the floor, completely unwilling to work. However, because Misaka Mikoto kept working, she was inspired by her earnestness and joined the cleaning team.

"And so...without realizing it, we've arrived at this day together..." Misaka Mikoto pulled a carefully packed, beautifully wrapped paper bag from her purse. "If we're talking about an anniversary that belongs to both of us...shouldn't it be today?"

"!" Shirai Kuroko stared at the paper bag, her body involuntarily moving towards Misaka Mikoto. Taking the bag, she instinctively asked, "C-can I open this?"

"certainly!"

Shirai Kuroko opened the paper bag, inside was a light yellow short-sleeved T-shirt with cute rabbits and letters on it. Shirai Kuroko hugged the shirt to her chest as if she had found a treasure.

"We'll always be together from now on... Please take good care of us~"

"Sister...Big sister, you just said...we'll always be together..."

"Of course, we don't study at the same school or live in the same dorm. We're inseparable, partners!"

"Here you go!" Misaka Mikoto handed over Shirai Kuroko's cup, while she herself took Wanai Kinuho's cup.

"Cheers to our partnership!"

"For the sake of that red thread of fate that connects us!"

"So that we can be each other's roommates"

The two cups clinked together, and the two drank from them. After Misaka Mikoto finished drinking, she smiled and put the cup back, while Shirai Kuroko remained silent.

Shirai Kuroko felt a strange burning sensation spreading through her body. It wasn't pain, but it was far more unbearable. And her mind seemed to be malfunctioning. She looked down and realized she had been drinking the beverage she had laced with aphrodisiac.

"Big sister~ Since we're cleaning the pool... it'll be more appropriate to wear a swimsuit that gets wet~" Shirai Kuroko said, sitting by the pool, her voice drawn out and distorted, making one's back tingle.

"Huh?" Misaka Mikoto looked back at Shirai Kuroko with a puzzled expression, but didn't find anything unusual, so she turned back to cleaning. "But it's such a hassle to go back and get it..."

"Hehe~ Actually, I expected this to happen~" Shirai Kuroko turned around and opened her backpack: "Ta-da! I brought Onee-sama's swimsuit~"

Before she could finish speaking, a long-bristled brush slammed into Shirai Kuroko's face, and Misaka Mikoto's angry voice rang out at the same time, "I remember it was in a locked cabinet..."

"Uh..." Shirai Kuroko stood up, the face brush falling to the ground, leaving a red mark shaped like brush bristles and a ring of detergent foam on her face. "Before my abilities... a mere lock is nothing..."

"Come on~ Enjoy yourself~" Shirai Kuroko leaped into the air, and Misaka Mikoto instinctively took a step back to avoid being hit in the face. However, Shirai Kuroko instantly teleported behind her, one hand reaching into the sleeve of her shirt and the other hand reaching under her skirt.

In an instant, Misaka Mikoto felt as if something had vanished, leaving her only in a white shirt and a gray pleated skirt. When she came to her senses, her face flushed red, and she covered her body with her hands.

"My dear older sister... wearing such childish underwear again..."

"Give it back to me!"

"So... let's change into swimsuits..." Shirai Kuroko was saying when she suddenly noticed something. She picked up Misaka Mikoto's T-shirt and the T-shirt Misaka Mikoto had given her. To her surprise, the two T-shirts were exactly the same except for the color.

"Oh my? Oh my, oh my~" Shirai Kuroko held up the clothes with both hands, dancing and singing with delight, "It's a set, it's a set! A set~ A set~ It's a set with Onee-sama~"

"Kuroko—!" Misaka Mikoto shouted in embarrassment and anger, her voice so loud that even the warehouse outside could hear it.

Having just returned and changed into their swimsuits in the warehouse, Wanai Kinuho and Awafuki Manbin opened the warehouse's iron gate and peeked out. Awafuki Manbin picked up his bag and went outside. "It feels so lively here..." Wanai Kinuho followed him out. "Misaka-senpai, the routine check-up is over, I'm here to help..."

Just as the two focused their attention on the center of the pool, they happened to be struck by Misaka Mikoto's electric current, which knocked Shirai Kuroko to the ground.

"Oh my gosh~ Big sister's beloved whipping~"

"Stop talking! Give it back to me! Give it back to me!"

"No way..."

"I told you to give it back to me!"

Upon witnessing this outrageous scene, the two turned around simultaneously and closed the warehouse door. "Let's pretend we didn't see anything..."

"That's...that's true..."