Shisui Uchiha was only ten years old when he was shocked with probably the biggest bombshell of his lifetime. Not even the recent kyuubi attack from the previous month had him this shocked up until now. His mother passed away several years ago when he was about three years old. Shisui's father, while still grieving up until his passing, had soon moved on and focused his efforts in the war.

That's what Shisui assumed had only happened throughout his childhood. He was wrong.

Shortly after his father's passing, the dark haired Uchiha was sharpening his kunai, shuriken, and other tools on a late evening in his home. Hearing three audible knocks at his front door, Shisui got up from his living room table, expecting to see his friend Itachi there for a late night training session or hangout.

Shisui reached out to turn the knob of the front door, gently creaking it open with a slight gust of cool night air. The winter season was soon to be coming, with the nights growing colder and colder. Strangely, when the young prodigy opened the door, there was no one there. Hearing a slight whimper, his dark eyes quickly snapped down to his feet.

There was a baby swaddled up with a note tugged into one of the folds of the blanket. Confused, the young Uchiha carefully reached down, picking up the visibly newborn infant before bringing it inside. Shutting the door behind him, Shisui walked to his bedroom and placed the sleeping infant on his bed before sliding out the folded note. Sitting on the edge of his bed, his eyes scanned the note, searching for answers. After a few moments, his eyes widened in shock.

"If you are reading this letter, this means I have already passed. I have entrusted this child with this letter to be handed off by a close friend. Your father is the father of this child, your half-sister, who is the child of myself, a Hyūga. Please take care of her, and please keep her identity a secret. With complications from the pregnancy and needing to keep her existence safe from the village and the Hyūga clan, I have entrusted her wellbeing to you. Please take care of her, Shisui Uchiha. When you're done, please burn this letter."

Tearing the letter in half, Shisui got up and tossed the pieces into the burning fireplace in his living room. He sighed, pinching the bridge of his nose, 'What did my father get himself into?'

Hiruzen Sarutobi, the Third Hokage of the Hidden Leaf Village, sat at his desk one early morning. Stressed from several meetings, mission assignments, and signing off several documents, the Sandaime Hokage finally had some downtime to take some rest with just a few meetings for the day. It was a short relief from the overwhelming chaos brought on by the Third Great Shinobi War.

Hiruzen let out a breath of smoke from his pipe, gazing away outside his office. Two curt knocks rapped against the door of his office.

"Come in," he responded firmly.

Shisui Uchiha stepped through the door and walked to the middle of Hiruzen's office before kneeling down, his right pale fist placed against the wooden floor.

Knowing who his new guest was without having to check, Hiruzen slowly inhaled another stream of smoke from his pipe, "Shisui Uchiha, what brings you here to my office?"

A few moments passed, the clan's pride not fully knowing how to approach the man with the news of his newborn sister. "Hokage-sama, I beg that what I'm about to tell you is to remain a secret within these walls. I hope this isn't too much to ask of you."

Hiruzen walked back to his seat, resting his bronze smoking pipe gently on his wooden desk, "It depends on what you're asking of me. Tell me, boy."

"I have a newborn half-sister, Hokage-sama. She was left on my doorstep last night with a letter that I burned. Her mother is a Hyūga who is unknown and deceased. The letter advised that her existence remains a secret, which I believe we both have a feeling as to why."

Hiruzen certainly did not expect to hear this. This was news. While it wasn't entirely too uncommon for both the Uchiha and the Hyūga to marry and fornicate outside of their clans, it was rather looked down upon for them to interfere with other major clans and families. It could cause legal issues and tension. Even then, most Uchiha and Hyūga were expected to marry individuals of higher status or within the same clan.

And it was certainly suspicious that the mother would hide such a pregnancy.

"This is… where is the child right now?"

"I have Itachi Uchiha looking after her right now, Hokage-sama," Shisui replied.

Hiruzen nodded, "Alright. Considering the circumstances around the recent kyūbi attack and the aroused suspicions towards the Uchiha, this must remain a secret for the sake of peace in the village. If not that, but peace for your sister. I already have an idea for a cover story so that the child is able to exist with no political interference."

Shisui nodded in agreement, "And what solution do you propose?"

The war veteran smiled, the tip of his red hat lifting as he raised his head just a bit, "You've already thought of a name for the child, haven't you?"

Shisui gave a slight smile, "Yes, Hokage-sama. I named her Kotone."

Hiruzen nodded, "Then her name shall be Kotone Uchiha. Her mother's identity shall be unknown and remain a secret until necessary, and she will be simply known as the child of both a civilian and an Uchiha. Kotone will be officially registered as your half-sister. I'll have everything arranged and meet with Fugaku about this as well. Only you will know about her true identity."

Shisui nodded in relief, "Thank you, Hokage-sama."

Kotone Uchiha was a very beloved addition to the clan. While many clan members were a bit confused about where a newborn came from and how she came to be Shisui's younger half-sister, there wasn't much pushback to it at all.

While busy with missions and the war, Shisui often left Kotone at the local daycare or with Itachi to take care of. Itachi wasn't one to really mind, afterall, he absolutely adored taking care of Sasuke, his new baby brother, so what was one more to take care of?

One admirable trait (or maybe unadmirable trait by the more traditional Uchiha members) was Kotone's eyes. Kotone had the typical dark hair color of an Uchiha, but had light lavender eyes that stuck out against the dark contrast.

Kotone was a very cute baby. Shisui thought she was a cute baby. Who doesn't like babies? Especially his beloved younger sister? While Shisui was renowned as Shisui of the Body Flicker, and seen as this highly skilled shinobi, it was a very stark contrast for the respected Uchiha to be doting on a newborn.

It was a little comedic at times, Itachi noted. Itachi wasn't really one to talk either, though, as he practically did the same for Sasuke.

It was also an often occurrence that Shisui would bring little Kotone to set up playdates with Sasuke, which always went well. Itachi's mother, Mikoto, often enjoyed having Shisui and Kotone over whenever they could and even offered to babysit Kotone herself. While Fugaku, head of the Uchiha clan was often absent, even he grew somewhat of a liking to Kotone.

Itachi once overheard Fugaku even suggesting an arranged marriage between Sasuke and Kotone in the future to create a strong Uchiha lineage. They were both conveniently born within the same year, Kotone being the half-sister to the highly respected Shisui.

Itachi repeated this to Shisui, expecting his friend to be happy that even he and Kotone had some approval from the clan's head. They both sat across the wooden porch of Shisui's backyard, with Kotone laying on her back.

Shisui looked at Itachi with a disgusted look as he was changing the now one-and-a-half year old Kotone's diaper, "Fugaku said what?"

Itachi tilted his head, confused, "You don't seem pleased. Is this not good news?"

Shisui gritted his teeth, shaking his head. Itachi had never seen Shisui this angry, and boy was he angry.

"Of course not! Kotone can be with whoever she wants in the future, or no one at all!"

Now finished with the diaper, Shisui carefully put Kotone's yellow duck onesie on as he continued ranting, "Kotone can be whoever she wants to be, and I will support her on that decision."

Itachi sighed, "Well, it was merely a suggestion I heard, nothing set in stone."

Itachi learned another thing that day. Shisui was very loyal to Kotone's autonomy and livelihood, even if it went against the clan.

Kotone was five years old when she started the ninja academy. The little Uchiha, dressed in a simple dark blue dress and sandals gripped the fabric of Shisui's pant leg at the school entrance. Her dark black hair was tied back in a ponytail, with her bangs dusted across her forehead, a strand of hair swept in between her eyes. She was nervous.

Shisui, now fifteen, leaned down to give Kotone a hug, "Imouto, don't worry. You'll be the best ninja out there and impress everyone!"

Kotone released the hug, looking at her older brother hopefully, "Really?"

Shisui nodded, "Really. And you have Sasuke-chan there to help you. He's really brave and even went ahead inside the academy himself already, right Itachi?"

Itachi, previously just a bystander, nodded and gave Kotone a reassuring smile.

Kotone smiled back, a newfound determination across her face, "Okay!"

It was going to be her very first day of school, and she couldn't mess this up.

Leaving the two Uchihas, she ran ahead through the academy entrance, searching for her classroom. Once she found the correct one, she went ahead and found Sasuke, her beloved cousin.

Kotone and Sasuke were almost never separated. They adored each other as if they were actual siblings, to the point where they even addressed each other as such.

Sasuke had taken a seat in the front row of the classroom as other students shuffled in. Excited, Kotone sat herself next to Sasuke, smiling at him.

Kotone absentmindedly shook her leg against the desk, first day jitters making her both excited and anxious. Sasuke-chan gave Kotone a slightly annoyed look.

She gave a sheepish smile and immediately stopped, "Sorry onii-chan, I'm super nervous! How are you so calm?"

Sasuke gave a small smile, which quickly went away as fast as it came, "I don't know. I just want to make Aniki proud of me, and by doing that, I have to do my best."

It made sense, so Kotone nodded in understanding. The young Uchiha looked to her right at the door, watching as more students shuffled in. Finally, an adult which she assumed was their new teacher walked through the door.

He was a young, tan-skinned man with a scar across his nose and hair tied back into a ponytail. He was wearing the standard chunin outfit that Kotone often saw other shinobi in the village wear, along with the official forehead protector. Oddly enough, he looked somewhat familiar, as if she had met him before. Maybe he's a friend of Shisui-nii?

Their new teacher stood below in front of the chalkboard, smiling, "Hello, I'll be your new teacher and you can call me Iruka-sensei. I'll now be taking attendance and we can start off with our introductory lessons."

Iruka-sensei called out names, each student raising their hand and giving a verbal confirmation. Sasuke and Kotone's turn eventually came along with some whispers of the students behind them.

"Uchiha? There's two of them in this class? Are they siblings?"

Kotone sweatdropped. Did they really think we couldn't hear them?

Soon after, Iruka called out another name, his eyes shining with… disgust?

Kotone frowned, furrowing her eyebrows in confusion.

"Uzumaki Naruto."

"Here!"

Uzumaki Naruto? The name sounded familiar. Really familiar. She turned her head up towards the back of the classroom, up the steps of the ascending rows of desks and saw a boy raising his hand.

He was blond, had blue eyes, and had weird whisker markings on his cheeks. She slowly blinked her lavender eyes, trying to figure out where she might've seen him before. He wore a dark long sleeve shirt under a regular white t-shirt that had a red swirl adorned on the front as well. Maybe a clan symbol?

Before little Kotone could give up on trying to remember who the strange boy was, his eyes drifted to hers. Feeling embarrassed for getting caught while staring, she gave him a small wave.

Naruto was a little confused. Normally, most of the other kids and adults often ignored him or gave him mean glares and remarks, but this was honestly one of the first few times someone looked at him as a normal person. It was weird.

The blond boy gave the friendly girl a confused look before smiling back and giving a small wave of his own. Kotone turned her head back to the board.

Maybe she should play with Naruto at lunchtime?

Once lunchtime finally arrived after Iruka-sensei's lecture, the students were all free to eat lunch and play. Kotone had her own bento inside her desk, which she pulled out to eat. Sasuke had also done the same. Most of the students went outside to eat their meals, while some were allowed to stay inside.

Naruto, on the other hand, just sat in the back corner of the room, not eating anything. Feeling a bit bad, Kotone got up from her seat and walked up the steps to Naruto.

Once she had reached his desk, his blue eyes stared up at hers in slight confusion and hesitation.

She smiled, "Hello. I'm Uchiha Kotone. What's your name?"

Naruto stared at her for just a moment, a bit startled. At first, he didn't trust her perceived kindness, but after looking into those bright, genuine lavender eyes of hers, she didn't seem like she was lying. Naruto decided to chance it.

He smiled, "I'm Uzumaki Naruto! Nice to meet you!"

Yes! A new friend. Kotone gave Naruto her hand, to which he stared at in confusion.

"Do you want some of my lunch? I saw that you didn't have any food on you, and you looked lonely, so…" she paused awkwardly.

Naruto gaped at Kotone in shock. Why was he shocked? Was she too upfront? Oh no, was she being creepy?

The boy shook his head in disbelief, "You're not joking around?"

She shook her head.

"Okay."

Kotone clapped her hands and jumped, shocking the poor boy, "Yay! A new friend! I can't wait to have you meet my favorite cousin!"

At the mention of his title, Sasuke's eyes snapped in their direction. He looked annoyed. While Sasuke had his nice moments, he always tried to copy his brother and act like a stoic, cool, edgy Uchiha in public. It got worse as they got older.

But that's okay, that just left room for Kotone to find more ways to tease him in public and force him out of his shell. And Naruto would be perfect to help with exactly that, too.

Kotone gave a friendly grin at Naruto as she tugged him over to her previous spot, plopping him down on the other side of her seat.

It was the start of a beautiful friendship.

Hope you guys enjoy this new story! And yes, this will be a Naruto x OC fic but it's gonna be a slow burn and is definitely going to take a turn for the worst... expect some angst sooner or later ahaha!

Please leave reviews! They are my main motivation!