Chapter 7: The Lanterns
"Is that so?"
Iruka's expression was somewhat surprised as he glanced at Tsuruma Nobuyuki's leg, noticing a faint bruise. He quickly stifled a laugh.
Nobuyuki, confused by Iruka's reaction, furrowed his brows. "What's so funny, Iruka-sensei?"
Iruka chuckled before shaking his head. "It's nothing. I just realized something."
Nobuyuki tilted his head slightly, waiting for an explanation.
"Although it's only been half a month since we started training, I unconsciously started treating you as an adult," Iruka admitted. "But now, seeing you get so competitive that you end up injuring yourself... it made me realize—you're still just a kid."
A genuine smile spread across Iruka's face. "I couldn't help but laugh. Sorry!" He pressed his palms together in an apologetic gesture, but the amusement in his eyes didn't fade.
Nobuyuki didn't mind Iruka's laughter. If anything, it felt like the barrier between them had thinned a little.
Previously, Iruka's approach to him had always been formal—professional, but distant. It was as if he saw himself more as an instructor upholding his responsibilities rather than a mentor who truly cared.
But now, there was something different.
If there were a favorability system like in a game, Nobuyuki mused, maybe he'd see something like "Iruka's favorability +10" pop up right now.
Still, he didn't dwell on the thought for too long.
Iruka, misinterpreting Nobuyuki's silence as a sign of lingering embarrassment, stopped laughing and cleared his throat.
"Alright, alright. My bad for laughing," he said, waving his hand dismissively. "How about this—I'll make it up to you by teaching you a new technique."
Ninjutsu?
Nobuyuki immediately perked up. His soreness from training vanished from his mind in an instant.
Over the past two weeks, he had focused on improving his taijutsu under Iruka's guidance. His progress had been steady, and he had even reached Taijutsu Level 2 recently. However, he had quickly realized that physical training had its limits.
Taijutsu experience points could only accumulate so fast. No matter how much he pushed himself, his body had real limitations. Soreness, fatigue, and muscle strain couldn't be ignored.
In contrast, ninjutsu provided another path for growth—one that wasn't bound by raw physical endurance.
If he could master a new technique, it would not only make him stronger, but it would also give him more ways to grind experience points.
Excitement flashed in his eyes as he looked at Iruka. "Really? You're not joking, right?"
Iruka smirked. "Of course not. But don't get too excited just yet."
He took a step back and crossed his arms. "The technique I'm about to teach you isn't something simple."
Nobuyuki didn't care about that at all.
The harder the technique, the better.
If it was difficult to learn, that meant it would provide more experience.
So, without hesitation, he bowed respectfully. "Thank you very much, Iruka-sensei."
Iruka shook his head with a small smile. "Wait here for a moment."
With that, he vanished from the training grounds in a blur of movement.
A Few Minutes Later...
After four or five minutes, Iruka returned, carrying a large scroll nearly half his height.
Nobuyuki's eyes widened.
He had seen ninjutsu scrolls before—he had learned chakra refinement from one left behind by his deceased father. But that scroll had been relatively small, only about the length of his forearm.
In comparison, the one Iruka was holding was massive.
Could it be a B-rank technique or higher?
Did he just get lucky?
Nobuyuki instinctively rubbed his chin, a habit carried over from his past life. But when his fingers brushed against smooth skin instead of stubble, he remembered that he was still a kid in this world.
Iruka, noticing his thoughtful expression, smirked. "What's on your mind, Nobuyuki?"
Nobuyuki snapped out of his thoughts and grinned. "I was just wondering if I've suddenly become the protagonist of some legendary story—meeting a hidden master at school who's about to teach me a peerless technique."
Iruka let out a short laugh before reaching out and ruffling Nobuyuki's hair.
"Then you're going to be disappointed," he teased. "I'm just an ordinary academy teacher—not a hidden master, and definitely not someone with a secret, forbidden technique to pass down."
Nobuyuki frowned, shaking off Iruka's hand. "Alright, alright. So, what's actually in the scroll?"
Still smiling, Iruka knelt down and unrolled the scroll on the ground. As he spread it open, he explained, "This isn't a ninjutsu scroll, Nobuyuki. It's a sealing technique."
Nobuyuki blinked. "Sealing technique?"
Iruka nodded. "This was left behind by my father. It's called the One-Thread Light Formation."
Nobuyuki's excitement didn't wane in the slightest. He had expected a standard ninjutsu, but a sealing technique was even better.
Sealing techniques were rare, complex, and extremely useful. Even in the Boruto era, where technology was advancing rapidly, sealing techniques remained a fundamental force in the ninja world.
More importantly, sealing techniques were scalable.
While an E-rank jutsu might not seem powerful at first, advanced applications could lead to devastating abilities—like the Reaper Death Seal or the techniques used by the Uzumaki Clan in their prime.
Iruka continued, "Although this technique is only an E-rank jutsu, it's an introduction to the world of sealing. It's a bit difficult to learn, but unlike ninjutsu, it doesn't pose any physical risk. At worst, it'll just give you a headache from overthinking."
Nobuyuki was already reading through the scroll as Iruka spoke.
As he skimmed through the contents, he quickly understood why Iruka had warned him about the difficulty.
The principles behind the One-Thread Light Formation were completely different from standard ninjutsu.
To put it in simple terms, learning sealing techniques was like learning a foreign language—but without a dictionary.
The symbols and patterns used in sealing techniques weren't intuitive. They were built upon centuries of knowledge, refined by various clans, and required precise chakra control to activate.
Still, Nobuyuki wasn't discouraged.
Difficult? That just meant more experience points.
Iruka watched him for a moment before asking, "Do you have any questions so far?"
Nobuyuki took a deep breath. "Just one."
"What's the actual function of this technique?"
Iruka smiled. "Good question. The One-Thread Light Formation is a minor binding jutsu. Think of it as a weaker version of the Shadow Imitation Technique used by the Nara Clan."
Nobuyuki's eyes gleamed with interest.
"It creates a thin, nearly invisible thread of chakra that extends outward. If it connects with a target, it binds them in place—though only slightly. The restriction is weak, and it's easy to break free from, but it's still useful for minor immobilization."
As expected of an E-rank jutsu, its effects weren't particularly powerful.
But Nobuyuki didn't care.
Because what mattered wasn't the current strength of the technique, but its future potential.
Sealing techniques had a long history of evolving into terrifying abilities. If he kept developing this, who knew what it could become?
Iruka clapped his hands together. "Alright! No more theory. Time to put it into practice."
First Attempt: Failure
Nobuyuki nodded and took a deep breath.
He carefully followed the instructions on the scroll, forming the necessary hand seals and channeling his chakra into the formation.
Then, with full concentration, he activated the One-Thread Light Formation!
…Nothing happened.
Iruka burst into laughter. "Hahaha! As expected, you failed, Nobuyuki!"
But Nobuyuki grinned just as widely.
Because in the corner of his vision, a notification had appeared:
Sealing Technique – One-Thread Light Formation: Lv 1 (1/100).
Failure? No, this was just the beginning.
With enough repetition, enough practice, and enough experience…
He was going to master this.