Chapter 1: My Sister is Sasuko
The Uchiha compound in Konoha basked in the dying light of day.
The evening sun painted the training ground crimson, its vast expanse empty save for a small figure who continued practicing her shuriken throws with tireless determination. Crystalline beads of sweat traced down her pale cheeks, dampening the front of her training outfit as she focused intently on her target.
"Sasuko, that's enough for today," called out the lazy voice of a young man lounging against a crooked tree, a leaf dangling from his mouth. "If we're much later getting back, Mother will lecture us again."
"No way! I'm definitely going to master the shuriken technique that big brother taught me today!" The twin-tailed girl with raven hair glared at him as another shuriken whistled through the air, embedding itself dead center in the target.
"Besides, you promised to practice with me, so why am I the only one actually training while you've been slacking off this entire time, Yu!"
"Why indeed?"
Because someone's watching us from the shadows.
Yu remained silent, his eyes narrowing as he studied the distant bushes with calculated interest.
ROOT's surveillance has been getting tighter and tighter...
When he failed to respond, Sasuko puffed out her cheeks indignantly and stomped her foot. "There you go again, saying half of something and then stopping! Riddle-makers should get out of the Uchiha clan!"
Her clear, childish voice echoed through the forest, startling several crows into flight as they fluttered toward the darkening sky.
Yu watched Sasuko's flushed face, warmth blooming in his eyes as he smiled gently. "A dead-last like me doesn't have Itachi's kind of talent."
He stretched lazily, sunlight filtering through the leaves to cast dappled shadows across his handsome profile. "Training would just be a waste of effort anyway. I'd rather save my energy to carry you home afterward."
"Hmph... well, since you're just a dead-last... I guess I'll forgive you this time."
Sasuko kept her head down, unconsciously fidgeting with the hem of her clothes as her voice grew quieter and quieter.
Stealing a glance at the young man's smiling eyes, she hurriedly turned her face away, though the tips of her ears betrayed her with a telltale blush.
Yu noted the darkening sky and gracefully leaped down from the tree branch, landing softly as leaves drifted down around him. He brushed the foliage from his shoulders and crouched in front of Sasuko.
"It's getting late. If we don't head back soon, the dumpling lady really will close up shop."
"I want five skewers!" Despite her demanding words, Sasuko obediently climbed onto Yu's back, wrapping her arms around his neck.
Feeling her slight weight settle against him, Yu steadied himself and stood.
"Two skewers at most, or you won't have room for dinner."
"Hmph!" Sasuko puffed out her cheeks. "I'm the young lady of the Uchiha family! A few rice dumplings are nothing..."
"Still not happening."
"Yu!" Sasuko huffed directly into his ear. "You're so mean!"
...
As the gentle breeze caressed his face, Yu carried Sasuko on his back while watching the sunset, his thoughts drifting.
It had been twelve years since the Uchiha clan leader adopted him and he arrived in this world.
His previous world had been a post-nuclear wasteland dominated by magnetic field powers. The strong were classified by their power levels in horses, while the weak barely survived in the irradiated wilderness. It was a brutal, violent place where civilization struggled between raw power and total destruction.
He'd been fortunate enough to be one of the rare individuals who awakened magnetic field abilities, but unfortunately, he could barely manage electrical current manipulation—still nothing more than an ant in the eyes of true magnetic field masters.
That day, he'd only heard rumors of two legendary fighters engaging in an earth-shaking battle over the ocean, their conflict so intense it tore up the very seabed.
The aftershocks affected the entire planet. Towering tsunamis crashed into cities, volcanoes erupted with millennia of accumulated fury, and thick smoke shrouded entire continents.
If the apocalypse had a face, that would have been it.
He'd died in that catastrophe. In his final moments, he felt some regret, but mostly relief. As an orphan trying to survive alone in that hellish world, he'd simply been too exhausted to continue.
When he opened his eyes again, he found himself in this world.
On that midsummer night, the evening breeze rustled through the leaves with a gentle whisper.
A pale-skinned young woman with a cinnabar mark between her brows tenderly lifted his infant form into her arms.
"Oh, what an adorable child."
"Those eyes... Three Tomoe!" came a somewhat stern male voice.
"How strange. Why isn't such a small child crying at all? What could he have experienced..." Mikoto gently touched his nose with her pale finger. "Oh my, his eyes changed back."
"That's normal. The child is too young—his chakra can't maintain the Sharingan for extended periods," Fugaku explained from beside her.
"I wonder whose child this is. If someone abandoned him carelessly, they should be severely punished when we find them."
"Let's return to the clan first and ask around. If no one claims him... honey, I'd like to adopt him."
...
Listening to the couple's fragmented conversation, drowsiness overcame him. His head grew heavier and heavier until, after one last look at the gentle woman, he closed his eyes.
As expected, no one claimed the baby who seemed to appear from nowhere. During those turbulent times, no one wanted an extra burden.
Since he was found in the forest on that midsummer night, Mikoto named the child Yu—Uchiha Yu.
Fugaku publicly announced his intention to adopt the boy.
For these twelve years, the couple had treated Yu as their own son.
But when Yu was very young, Fugaku repeatedly warned him to hide his talents well.
While Konoha appeared calm on the surface, dangerous undercurrents flowed beneath. ROOT, ANBU, and various clans—friction constantly simmered behind the scenes.
Fugaku initially hadn't wanted to burden such a young child with the adults' dirty politics.
But this child's talents were simply too outstanding. Konoha wouldn't tolerate the Uchiha producing a second Shisui—that would pose too great a threat.
The first time he'd taught Yu the Fire Style: Fireball Jutsu, the flames had reached an incredible twenty-meter range.
Consider that his eldest son—Uchiha Itachi, hailed as a once-in-a-century prodigy—had only managed fifteen meters on his first attempt.
A few years later, Lady Mikoto's second child was about to be born.
"Honey, if it's a boy, let's call him Sasuke. If it's a girl, how about Sasuko?" Mikoto lovingly caressed her swollen belly, her expression tender.
"Whatever you decide is fine with me." Fugaku rarely smiled, but his stern features softened with genuine warmth.
He thought to himself that their eldest son Itachi possessed extraordinary talent, and this child would surely be no different. The Uchiha clan's glory would rest on their shoulders.
"Yu, don't just stand there looking lost. Come here—you're going to be a big brother," Mikoto called gently to Yu, who seemed somewhat at a loss.
Yu walked toward Mikoto with awkward, stiff movements, unsure where to put his hands.
"Would you like to feel?" Mikoto gently stroked her rounded belly, beaming with joy. "The little one is kicking me right now. What an active child."
"May... may I?" Yu looked toward Fugaku with a mixture of anticipation and nervousness.
"Of course you can. You're our child too. Don't tell me you wouldn't like a little brother or sister?" Fugaku looked helplessly at his most promising adopted son.
This child was wonderful in every way, except he was far too well-behaved. Boys his age should be more mischievous—it wasn't good for them to furrow their brows like Itachi did at such a young age.
"Excuse me, Mother..." Yu finally extended his trembling hand and gently placed it on Mikoto's belly.
The powerful movement against his palm made his own heart race.
Time flowed like a fleeting horse, and six years passed in the blink of an eye.
Yu watched as that wrinkled little bundle in swaddling clothes grew into an energetic little girl who could run and jump.
Only he wasn't sure exactly when this little girl had become... perhaps a bit too clingy.