Konoha: Starting by giving Hinata the Tenseigan!

'This is the emblem of our Dimensional End's Congregation. Recite my true name, and you shall gain unexpected rewards, even those eyes of yours, brimming with such potential, may evolve.'

Night had fallen. Naturally, Hinata, having been scolded by her elders again, was confined to her room. 

She sat there quietly in her bedroom.

Yet her thoughts drifted back to the strange older boy she had met that afternoon.

"Could my eyes become pretty, too?"

Almost without thinking, she retrieved that delicate emblem. On its abyssal backdrop was a shining six-pointed star, casting a mysterious glow on this dark night.

"It's so beautiful… Then…"

"Natsuki…

"No, that's not right. That's not his true name."

"His true name is… Yuhi… Yuhi Natsuki!"

Cupping the emblem carefully in her small hands, Hinata spoke in a hushed yet determined voice.

It was late, and everyone else was likely asleep. She couldn't risk waking anyone.

That was just how gentle Hinata always was.

Besides, this was her secret…

"No reaction?"

Hinata frowned slightly.

She then recalled in detail how serious Natsuki had looked when giving her the emblem.

Natsuki wouldn't lie, would he?

Even though it was their first meeting, he had helped chase away those bullies for a complete stranger like her. Natsuki must be a truly kind person.

"Hoo…"

Hinata mimicked the way Natsuki had taken a deep breath, then surreptitiously glanced around.

No one was there!

Sure enough, as soon as she realized she was alone, her tense shoulders relaxed.

In the next moment, she opened her pink lips:

"I, Hyūga Hinata, the First Mage, bearing the name of the Eye of Daylight, extend my greetings to the great Master of Dimensions, the Sealer of Demon Gods, Yuhi Natsuki."

"Please grant me even more beautiful eyes!"

At that instant, Hinata's expression was full of reverence, and her voice grew stronger.

Suddenly, the six-pointed star on the emblem erupted with dazzling light, filling the entire room in an instant.

A clear blue sheen swiftly overtook Hinata's normally translucent irises, bright and lustrous, shining even more brilliantly than the stars above.

A vast power surged from her eyes, and her small body slowly rose, as though freed from the pull of gravity…

…

The Yuhi Clan was also a famed and noble clan in the Konoha, though it had gradually declined over the years.

Once, the most notable figures of the clan were Yuhi Shinku and his daughter Yuhi Kurenai.

Unfortunately, Yuhi Shinku perished heroically five years ago during the Nine-Tails' Rampage.

He died alongside Yuhi Natsuki's parents.

So, as kin within the same clan, Yuhi Natsuki had been taken in by Yuhi Kurenai when he was little.

Two orphans leaning on each other for support… yeah, right!

…

"Natsuki!!!"

Fresh from his public chūnibyō show, which had fully activated his system, Natsuki was feeling both excited at having finally gained his cheat power and slightly awkward. 

The moment he opened the door to his home, a furious shout greeted him.

"Where have you been messing around? Do you know what day it is?

"Today is your birthday, and it's also the day I got promoted to Chūnin. We were supposed to celebrate together. Why'd you vanish on me? Hic…"

Before she could finish, the girl named Yuhi Kurenai let out a huge, alcohol-soaked burp…

Natsuki, who had been feeling a bit guilty, softened his eyes, or rather, his single visible eye, then swept it sharply around the room.

Sure enough, there were several empty liquor bottles beside the young woman.

Yuhi Kurenai loved drinking, especially strong liquor. She was gentle and refined in public, but at home, her true colors showed. 

Most critically, she was a terrible drunk: once tipsy, she'd cause any number of ridiculous scenes, even throwing bizarre air punches.

From the time Natsuki turned five and could manage things on his own, he had begun hiding Kurenai's secret stashes of alcohol, doing whatever he could to stop her from downing a bottle every day.

No matter where she hid her precious liquor, Natsuki would find it. His interference led to plenty interludes. 

Eventually, Kurenai compromised: now she'd only drink on holidays, and only a little, under his scrutiny.

Anyone unaware might assume Natsuki was the older one, given how he supervised her.

"Wh-what are you looking at? These bottles were all drained by that brat Anko, not me. Damn it, she didn't even clean them up after she was done."

"I only had one… hic!!!"

"Two? Three bottles!"

Seeing Natsuki's expression, Kurenai, face flushed red, hastily tried to explain. 

Suddenly anxious (and intoxicated), she extended one finger, intending to claim she'd only had a single cup.

In her addled vision, however, that one finger turned into two… then three.

She ended up blurting she'd had three bottles.

"Alright, you drank so much that for the next six holidays, you're banned from touching alcohol."

Natsuki nodded grimly, his face dark.

"Six… how many is that? One, two, three…"

Kurenai, still dizzy, tried counting on one hand but quickly got stuck. Six sounded way too high. Immediately, she flared up:

"No way! That's too long! Who's the big sister here, me or you?

"Can't believe I changed your diapers and wiped your butt, only to have you boss me around now!"

Huh?

Changed diapers and wiped my butt? Please. As a transmigrator, did I really need that?

Heck, by 4 month old, I could change my own diapers.

I was walking at one, running by two, flying by three, beating up little monsters at four, and by five, I was already taking care of Yuhi Kurenai. 

I'm a Genius, right?

Otherwise, how else could I have survived the Nine-Tails' Rampage a few years back, when Kurenai herself was still just a kid?

This rate of growth had shocked even her. 

Even in a Naruto world where children mature early, you rarely saw a toddler running and jumping at two.

At least she took comfort in one thing: Natsuki was still a kid who secretly did chunni things, thinking she didn't notice. It amused her for quite a while, reassuring her that, yeah, he was just a little brat.

Right as Natsuki was about to argue and make Kurenai see reason—

"Oh, by the way, here's your birthday cake. Happy birthday, little brother!"

In a total about-face, Kurenai went from slamming the table in anger to producing a delicate cake box from behind her. 

Such a wild leap in mood.

"Heehee, that Anko tried to sneak a bite earlier, but I caught her and tossed her out. This cake is for my little brother."

"…"

Natsuki gave a soft sigh. It was obvious Kurenai had forced herself to stay awake despite being drunk, just so she could wait for him.

On the surface, he remained calm, but inwardly he felt warmth flooding his heart.

After all, Kurenai was effectively the only family he had in this world.

In the end, with his sister drunkenly rambling about "two slices" or "three slices," their little birthday celebration drew to a close…