After spending a few days recovering in Konoha, Uchiha Kai made his way back to the forest where he often trained—his excuse being that he needed to "train," but his motivations ran deeper.
Ryoko Uchiha still had strong feelings about this. Kai was a quiet and well-mannered child, but the emotional distance between him and his parents, Ryoko and Keisuke, had never quite closed. Despite raising him, the bond between them didn't resemble that of a typical parent and child.
It had been troubling at first, but after so many years, they had grown used to it.
They didn't particularly care about Kai's growing fame on the battlefield. Although they were proud that he had awakened the Sharingan—especially at the three-tomoe level—they were far more concerned about his physical condition and mental wellbeing.
Keisuke, as a father, took things more calmly than Ryoko. Kai had been on the battlefield for six years now; Keisuke understood that his son had developed a sense of judgment and independence.
After all, no matter how strong a shinobi becomes, if his body can't withstand the strain, it's meaningless. Keisuke, himself a capable ninja in his youth, was a testament to that.
Kai wandered into the familiar woods. Though he couldn't be certain, he had a nagging feeling he was being watched. He wasn't exactly a "background figure" anymore—his reputation had grown.
Unlike Imai Kenta, whose sensory skills were exceptional, or Aya Hyuga, who possessed the Byakugan, Kai didn't have the same detection abilities. Because of that, he avoided heading toward the place where he stored personal records. Instead, he focused on other pursuits—like training with Chidori.
The Chidori, entrusted to him via Namikaze Minato by Kakashi Hatake, came along with scrolls containing Kakashi's insights and battle experience. Kai hadn't had the time to study them properly until now.
Kai had always had an affinity for Fire Release, as was common for Uchiha. But his compatibility with Lightning Release was less certain. Still, he knew that chakra natures weren't fixed—additional affinities could be learned through effort.
He couldn't remember whether Sasuke Uchiha's lightning affinity was innate or learned, but he knew Sasuke had built many powerful jutsu from the Chidori base.
Chidori wasn't simple—it required both chakra nature transformation and shape manipulation. It was a high-level technique with vast potential.
What intrigued Kai most was how much could be developed from this one jutsu. Sasuke had created Chidori Nagashi, Chidori Senbon, Chidori Katana, and even Kirin—techniques that all stemmed from the original. In that sense, Chidori rivaled Rasengan in versatility.
"As expected of master and student," Kai thought, reading through Kakashi's notes. "Even their core jutsu show the same creative potential."
Rasengan, too, was a prototype—a chakra sphere with no nature transformation. Its strength came from how easily it could be infused with elemental chakra, like Naruto's Wind Release or Lava Release variants. In contrast, Chidori had already been shaped into its lightning form.
"But between the two," Kai concluded, "Chidori suits the Uchiha better."
He wasn't greedy—he only sought what worked best for him. And with the Sharingan, Chidori became not just usable, but deadly. That settled it. Kai began training in earnest.
The technique itself wasn't beyond him. During missions with Kakashi, Kai had used his Sharingan to observe and memorize the chakra flow and hand seals. He was no saint—he'd already copied Kenta's sword style. There was no reason he wouldn't also copy Kakashi's jutsu.
Still, imitation was one thing. Execution was another. On the battlefield, there had never been enough time to break down and analyze all the moving parts. That was why, even after acquiring the scroll, he'd had to wait until now.
Ninjutsu training was time-consuming. Kai's main challenge lay in developing Lightning Release chakra and refining its nature.
In the original book, it took Sasuke over ten days to master the basics of Chidori. Kai didn't flatter himself—he knew he might not be as talented as that boy who had yet to be born. So he wasn't in a rush.
If things got serious, he could always head to Konoha Hospital—after all, Kakashi was still recovering there.
Time passed, and good news kept arriving from the front lines, just as Kai had expected.
The Kannabi Bridge had been destroyed—by his hand. With their supply lines cut and their homeland under attack by the forces of the Yellow Flash, the Iwagakure forces in the Land of Grass were now isolated and doomed.
What puzzled Kai, though, was the sudden silence from the Uchiha elders. After Uchiha Jun and the others had visited him once, they hadn't returned—as if Kai had vanished from their radar.
Which was fine. Kai had never liked them. If they didn't bother him, he certainly wouldn't seek them out. At least for now, he was content avoiding them.
His focus was on mastering Chidori—finally adding a decisive, high-speed assassination technique to his arsenal.
Though Ryoko was frustrated with his obsessive training, she held her tongue. Every night, she quietly applied medicine to his right hand to aid in recovery.
"Chidori!"
After half a month of focused effort, Kai had finally solved the issue of lightning chakra and its nature transformation. Thanks to Kakashi's scrolls, his progress had been fast.
With a quick hand seal, Kai activated the jutsu. Arcs of lightning began crackling along his right arm. They intensified, difficult to control at first. He frowned—the technique was volatile.
But then his eyes flashed red—three tomoe swirling—and the control he gained was immediate. His body coordination sharpened. The lightning calmed under his will.
A high-pitched chirping filled the air—one bird, then two, then dozens. It swelled until it sounded like a hundred birds crying at once.
"Thousands of birds…" Kai murmured, smiling at the sound.
But his expression suddenly turned cold.
"You'd better come out," he said, voice laced with warning. "I won't guarantee this technique won't land on you."
He might not have detected a skilled sensor, but this presence wasn't hiding well.
"As expected of a battlefield shinobi. Sharp as ever, Kai-kun," came a voice from behind a tree.
Uchiha Jun emerged with a faint smile. "Don't get the wrong idea—I wasn't spying on your training. I have a message for you."
"Speak."
"The patriarch has returned. The others… they want to see you."