"Let's get training already, Kakashi-sensei!" Naruto shouted, jumping up and down excitedly. "It's about time you taught us the Chidori, ya know?"
Sakura glumly gave Boruto's dad a sidelong glance. Here he was, feeling so excited about Kakashi-sensei finally giving him the attention he so desperately craved— and he didn't even know that his future wife, Boruto's mum, had been kidnapped by the Hidden Cloud Village.
'At this rate, Boruto's dad's son will never be born,' said Inner Sakura cheerfully. 'Isn't this a good thing?'
And the worst part of it all was that Naruto couldn't be allowed to know about Hinata's disappearance. Tenten had a very specific four-man squad in mind for the infiltration of the Hidden Cloud Village, and he wasn't part of it. Naruto was just too obnoxiously loud for a stealthy mission…
The first member of the squad was Tenten herself, obviously; unlike Sakura, who had only watched the anime, Tenten had actually been to the Hidden Cloud in the world of the future, so she knew its location and some of its security flaws. Furthermore, it was her Space-Time Ninjutsu that would make the exfiltration of Hinata possible.
The second member was Karin, due to her innate ability to mask her chakra signature; an ability that some pure-blooded members of the Uzumaki clan had inherited from the Otsutsuki clan. Thanks to the Chakra Suppression Jutsu, she would be able to pass through the sensory bubble that surrounded the Hidden Cloud Village undetected! (Though Tenten had neglected to mention exactly how she had come by this information!)
The third member was Sakura, due to her powerful Genjutsu abilities being perfect for infiltration, since illusions weren't as flashy as certain Ninjutsu… and mostly due to her being the only person who could convince Karin to do something so reckless for someone whom she didn't even know.
The fourth and final member was Neji, mostly due to his Byakugan, which would prove essential to locating Hinata, but also due to his Gentle Fist Taijutsu being capable of quietly taking down enemies. Of course, Neji had been rather reluctant to go on a quest to save the princess of the main branch, but since Tenten had been the one asking…
…
Meanwhile, Naruto was still trying to make Kakashi's signature Ninjutsu work.
Ox! Rabbit! Monkey!
Naruto slowly and carefully performed the Chidori's hand seals, before thrusting his hand into the air and shouting out, "Chidori!"
…and nothing happened. Obviously.
"Come on," Naruto growled, wiggling his hand. "Just come out, already, will ya?!"
"Your natural affinity for Lightning must be quite low, Naruto," said Kakashi, shaking his head helplessly. "Rather than wasting time on flashy Ninjutsu that don't suit you, why don't we focus on firming up your fundamentals…?"
"The fundamentals are boring, ya know?" Naruto groaned, letting his arms fall to his sides. "I wanna learn a cool Jutsu!"
Even though Hinata was in a huge pinch, it wasn't as if Sakura could just drop everything and go to her rescue straight away. If she tried to escape now, then Kakashi would just catch her right away— it was better to wait for Itachi to incapacitate Team 7's leader.
'Soon, one of the legendary Sannin will come to the village and take Naruto on a training trip,' Tenten had told her. 'So, try to stick to Naruto as much as possible before then, so that you don't miss it. You'll have to ask the Sannin to take you with him, but somehow, I don't think that will be an issue for you. You can give him the slip when you get close to the border.'
When Sakura had asked Tenten how she knew this would happen (in an attempt to make her show her hand), Tenten had just winked at her mischievously and told her that she had her special sources.
"As if I'd believe that, Future Girl," Sakura grumbled to herself. "Why am I the one who has to get sexually harassed? You're the Tsunade fangirl, so you should be the one going!"
Though he didn't know it yet, Jiraiya's goal was to be found in Tanzaku Town, since that was where Tsunade, the future Fifth Hokage, was currently having fun gambling every day. The town was a popular tourist stop on the way to the Land of Hot Water, which was known for its high-quality hot springs. The Land of Fire's nobles would often stop there to gamble, before crossing the border to enjoy the hot springs.
As such, Tanzaku town was conveniently located in the north-eastern reaches of the Land of Fire; heading in that direction would only bring Sakura closer to the Land of Lightning, where Hinata had been taken. Basically, the plan was for Sakura to accompany Jiraiya and Naruto to Tanzaku, before ditching them and Reverse-Summoning the rest of the squad to her location.
'Welp, might as well keep training until then,' said Inner Sakura nonchalantly. 'Hm, do you think Sasuke-kun would notice us if we mastered the Chidori?'
And so, back to training it was. It was sort of a transmigrator's rite of passage/tradition to master all of the main characters' Jutsu, so she might as well get started with the Chidori, while Kakashi was still willing to answer her questions…
Now, according to Lord Orochimaru's mental imprint in Sakura's chest, one had to create a difference in potential in one's chakra in order to transmute it to the lightning nature, and the best organ in which to make this transformation happen was the spinal column; or rather, the spinal nerves within it.
"Imagine yourself as a lightning rod, with the earth under your feet having no charge," muttered Sakura, repeating the mantra of lightning Ninjutsu to herself. "Concentrate the negative charges on one end, and let the electricity flow by itself to release Ninjutsu…"
It's rather difficult to envision, but lightning chakra can either act as static electricity or as an electrical current, since chakra can be manipulated and moved at will.
An example of how lightning chakra can become like static electricity is the Chidori, in which one gathers a mass of negatively charged chakra in one's hand to deliver a shocking stab to a target.
As for examples of how lightning chakra can act as an electrical current, there are the Electromagnetic Murder Jutsu and the Lorentz Gun Jutsu. The first Ninjutsu fires a stream of electricity at a target, while the second generates a powerful magnetic field by circulating lightning chakra to launch a ferromagnetic projectile at an extremely fast velocity.
Ox! Rabbit! Monkey!
Sakura carefully formed the hand seals for the Chidori; gathering attributeless chakra in her spine, turning it into lightning chakra, before sending the finished product through her chakra pathway system to her right hand.
"Chidori!"
"Ouch!" Sakura yelped, as electricity sparked between her fingers.
The Ninjutsu fizzled out shortly after that; lacking experience, most of the chakra that she had moulded for the Jutsu had gone to waste; Sakura had produced about as many electrical charges as if she had rubbed a balloon against her pink hair.
At any rate, it was about as good a start as she could have expected with a mere 99% lightning affinity; Orochimaru's tips and tricks as well as Sakura's knowledge of high school-level science were doing much of the heavy lifting when it came to the mental imagery part of Ninjutsu…
'Speaking of Orochimaru,' said Inner Sakura lazily, 'we forgot to free Kin Tsuchi from her hiding place. It's been four days; at this rate, she's gonna die of dehydration, unless we let her out soon…'
"Ah," Sakura blurted out.
Upon seeing Sakura summoning lightning chakra for her first time, Kakashi's exposed eye widened in surprise. Could it be that she had been born with three natural chakra affinities, he wondered? First fire, then wind, and now lightning!? Normally, it took months for even the most talented shinobi to learn how to transmute their primary affinity!
Of course, Sasuke had got the hang of the Chidori almost immediately thanks to his Sharingan, but still, for a civilian-born shinobi, this learning speed was remarkable!