Ahem, Sasuke, maybe save the cuddly big brother act for later.
Naruto, who had been waiting patiently with his hands on his head for quite a while, finally cleared his throat to break the warm, cozy scene in front of him. The sun was already high in the sky, yet Sasuke showed no signs of stopping his affectionate clinging to Itachi. So Naruto spoke up, reminding him, "It's about time. We should start today's training."
"Ah, you're right…" Sasuke snapped out of it like waking from a dream. He turned his head instinctively to respond—and immediately caught sight of Naruto grinning mischievously at him.
Only then did the proud little Uchiha realize he'd just been shamelessly doting on his big brother in front of this annoying friend. The blush that had barely faded returned full force, spreading across his chubby cheeks. "W-Wait! Naruto, who are you saying was being all clingy?!"
"Oh? Whoever's blushing is exactly who I meant~"
"Y-You… Who are you calling a kid?! You actually look younger than me, you know!"
"…!"
Sasuke's offhand comment made Naruto pause. Wait a minute… If we go by the age in this life… wasn't I actually born a little after Sasuke?
That would mean… if Sasuke is a 'little kid'… then I am too?
Naruto suddenly found himself struck silent, caught in an awkward trap set completely by accident.
"…Why aren't you saying anything all of a sudden? Don't tell me… I was right, huh, Naruto?!"
"All right, Sasuke," Itachi cut in gently, either having noticed Naruto's flustered state or just at the perfect timing. "Naruto's right." His calm voice redirected Sasuke's attention, skillfully steering the topic back on track.
After all, Sasuke was still a child—sweet words easily satisfied him, and he ended up missing the rare chance to completely dominate the teasing exchange. "It's nearly noon. Most of the time you planned for training is already gone. If you keep goofing off, it'll be lunchtime soon."
"Ah! You're right… Hmph, since big brother says so, I'll let Naruto off the hook. For now."
'Whew, that was close. Saved…' Naruto patted his chest in relief. 'Looks like I need to be more careful how I tease this little guy… or I'll end up digging my own grave next time.'
Just as Naruto was quietly savoring the victory of preserving his big-brotherly image in front of Sasuke, Itachi's next words nearly made him trip and fall flat on his face.
"Speaking of which… it's this late already. Where's the jōnin in charge of your training?"
"J-Jō… Jōnin?"
"Hm? Oh, right. I forgot you two don't know how ninja ranks work yet…" Itachi said casually. "To put it simply, the person who's been guiding your training lately should be your teacher. Sasuke told me about your training earlier, and for someone to come up with the tree-climbing and water-walking exercises to develop chakra control in a gradual, effective way—that's not something a regular Chūnin would think of. That's why I assumed your instructor must be a Jōnin-level ninja."
"…Oi, Sasuke. You didn't tell your brother everything, did you?" Naruto nudged the equally stunned Sasuke with his elbow. "What Jōnin teacher? I've been the one training you this whole time!"
"He only asked me what kind of training I've been doing! He didn't ask who taught me… And I was in a hurry because we left late, so I didn't mention anything else. How was I supposed to know he'd assume you were a Jōnin…"
"Hah?! That's a thing now…?" Naruto glanced at Itachi, who was still calmly analyzing everything as if a real Jōnin had been involved. He was even trying to deduce this nonexistent person's identity based on the list of actual Jōnin he knew.
'No no no, this guy didn't mistake me for a Jōnin… he just made up a completely imaginary Jōnin instructor for us out of thin air!!'
…Although, technically, the chakra training method was something that would be taught by Kakashi Hatake, the future Jōnin squad leader of Naruto and Sasuke's Team 7… So Itachi wasn't entirely wrong, in a way.
"Whoa, so big brother knows that many Jōnin? That's amazing…!"
"Huh?! Hey, wait!! Now is not the time to be admiring your brother, you idiot Sasuke! Shouldn't you be explaining things to him?!"
"Nani? Why me, dumb Naruto?! Shouldn't you, the so-called 'Jōnin teacher,' be doing that?!"
"Mm? You're the one who didn't explain properly and caused the misunderstanding. Obviously, you should fix it~"
"…That kind of makes sense—No, wait! Why am I—?!"
"…What's going on?"
Itachi was finally pulled out of his thoughts by the escalating argument. He looked over in confusion, only to find two squirming, red-faced kids trying not to laugh. "Did I say something wrong?"
"Ahem… There's a bit of a misunderstanding. But not entirely." Sasuke's eye twitched as he glanced at Naruto, who was now whistling and pretending this had nothing to do with him.
Sasuke took a deep breath and said carefully, "Yes, someone did guide me in tree-climbing and walking-on-water training. But that person… wasn't a Jōnin. In fact, he was already here before we arrived at the training ground."
"What?"
Itachi was surprised. As far as his senses could tell, aside from these two kids, no one else had been nearby at all. That could only mean… the supposed Jōnin had been hiding his presence the whole time?
'To remain undetected this entire time… That's the level of a true Jōnin.'
"…No, no, it's not like that…" Sasuke, now mortified, covered his face with one hand while raising the other to point at Naruto—who was shaking from suppressed laughter and watching everything with great interest.
"I wasn't trained by a Jōnin… And, big brother… you already saw him when you got here."
"What? I already saw him? Where?" Itachi followed Sasuke's finger, eyes scanning the snow-covered forest—only to land on a trembling, red-faced Naruto.
Confused, Itachi turned back to ask more questions—then froze, eyes wide, staring directly at Naruto's innocent, blinking face.
"Wait a minute… Sasuke, don't tell me… the one who trained you is…"
"…You probably won't believe it… but yes. It's exactly who you're thinking, big brother."
"Th-This… How… is that… possible?!"
…
December 14, Year 51 of the Hidden Leaf Village Calendar.
This was a day Uchiha Itachi would never forget.
The day he first met Naruto, the Child of Prophecy.
And the day his entire worldview got reset.