Note: This idea in my head didn't want to leave me, so I wrote this. Basic premix: the scientific method applied to chakra, results applied to fights. Don't expect any HPMOR-rationality, though. It's more in the line of "Let's see how much we can f this up without breaking it wholesome."
"Okay, let me get this straight. Chakra is this mythical life-force. Everyone is producing it, everything even. And people can, with training, influence this and force it to act."
Naruto nodded. He wasn't sure why he had actually started talking to this civilian kid in Wave, but it was an interesting conversation. The girl sitting across from him was the daughter of one of the bridge building craftsmen, helping her father by handing him tools and material. Essentially the same work Naruto and his clones did, since neither of them could help in the craft of building the bridge. But legwork they did freed up the experts for other stuff, making the whole project take that much less time.
Be that as it may, it was clear the girl wouldn't exactly follow her father's footsteps, not directly. Her mind was too inquisitive, too curious, wondering if maybe other materials would work better than those they used now. Would iron nails be better, or steel? Maybe wooden nails instead, in consideration of the damp climate of Wave?
"Yeah. Kind of? You have the physical energy in your cells, and your mind energy from your mind and you mould them. Iruka-sensei said that's like making steel with iron and coal, but I think of it like mixing milk and cocoa. You can't separate them after, right? And it's like you mix them in your stomach, but I never tried that because cocoa powder is so dry I can't swallow it…" Naruto continued to ramble as the girl opposite him furrowed her brow.
"So why don't they teach it to everyone? I've seen what you've done," Naruto had winced at that, but didn't say anything. He knew she was referring to a more general picture of what he, as a ninja, had done, not the gruesome actions that had taken place on the bridge, the killings he had taken part in. "It seems like people could do a lot with that kind of power. All the Naruto clones, for instance, and the walking on trees stuff. By the way, is that limited to trees?"
Naruto was still too trusting and starved for friendship to wonder if he was being spied upon by some other ninja. He honestly thought she was just curious and he didn't mind talking about his job and what were nominally not exactly state, but at the very least professional secrets. Beside, what could one girl at their age do, one who had never had any chakra training like the academy students had had? Her chakra coils were on a civilian level, so even if she somehow learned to mould chakra, it would amount to very little capability. Not even remotely anything in the same ballpark as he would now expand upon.
"Not only trees! Anything I concentrate on, I can walk on. Doesn't matter what it is!"
"Huh." The girl was a bit dumbfounded at that. Then a curious gleam went into his eyes. "D'you mind to test it?"
"What do you mean?"
She rummaged through her pockets for a treat her father had given her not too long ago. Food was still hard to come by, especially candy, but if she could expand her knowledge about the capabilities and limitations about this 'Chakra' she would certainly think it worthwhile.
"Here." She put the candy on the tabletop. "I bet I can find something you cannot walk on using chakra." She shoved the candy into the middle of the table. "Do you accept the bet?"
The blond ninja was both intrigued and suspicious of the bet. On one hand he wanted both to show off his prowess in the ninja arts, and of his ninja way, on the other hand he knew the girl only a little. He didn't even know her name yet…
"But what will you gain from this bet?"
At this the girl showed a toothy grin. "Something worth a thousand candies: knowledge."
That didn't exactly mollify the young ninja. He may not have had the highest marks in the academy (quite the opposite, actually), but that didn't mean he did not pay occasionally attention or managed to snatch the one or other bit of useful information from the teachings. Among them was quite a bit on information, and its worth inside the ninja world – and outside. So Naruto knew the girl was right, in a certain sense: knowledge could be worth magnitudes more than a simple piece of candy.
Albeit that candy looked awfully delicious… And she didn't ask for any real secrets, not anything she couldn't come by if she tried some other means… Oh well, what could possibly go wrong?
"Okay, then. What do you have in mind?"
A few days later the both of them stood next to a building on the outskirts of the town, near the street that lead to the soon-to-be-completed bridge. It had simply taken that long for Naruto to have some spare time again. The leader of Naruto's team had placed the three ninja under his care on a rotating schedule. Every day one of them was helping in the construction of the bridge, while the other two spent the day sparring and receiving lessons and instructions in various ninja techniques by their leader. That way he could ingrain the lessons deeper, while giving each of them focus as well as granting them the chance to recuperate somewhat, both mentally and physically, by helping the other workers on the bridge.
Nominally the three children had already had finished the tree-walking exercise given to them by their team leader days prior. After their much higher ranked ninja-instructor had shown them what one proficient in that simple exercise could actually do – walking around the trunk of the tree, lying on the underside of a branch, standing upside down for as long as he cared to – both his team mates Sakura and Sasuke, as well as Naruto himself, decided they could still improve.
After all, merely having a skill did not mean one had mastered it.
Pulling out a notebook and a pencil from her bag she flipped to a new page and wrote on the very top: Ninja notes.
"Okay, let's begin simple. Can you walk on a wall?"
Naruto snorted at that. "Pshyeah!" He took a few steps to the building, placed a foot on the side of it and walked in the strangest disregard of gravity the girl had ever seen. Once he was a meter and a half off the ground, she asked him to stop.
"Wait, hold your stance. Keep standing there while I take your time." They girl started counting out seconds as best as she was able to without any watch or clock nearby. After reaching twenty she started making scratch marks while talking to the ninja who was casually defying gravity, though by now not so nonchalantly anymore.
"Why~?" Naruto groaned. He didn't want to stand all the time in the same spot, and the physical tension of keeping his body parallel to the ground was getting to his calves and back muscles.
"Because you want candy and I at first wanted to know if you needed to move constantly to walk on walls." As she finished writing that down into her notebook she looked up at the visually straining Naruto. "Case in point: you don't."
Finally the ninja couldn't take it anymore and put out his arms out before collapsing to the ground. Gasping for breath he rolled over on his back.
"I didn't remember it being this hard!"
"Maybe it wasn't? How long did you hold your position your last time?"
"I don't know? The last times we were running up trees, marking how far we came until we reached the top. Sakura was the first, and Sasuke and me competed who'd reach the top next."
The girl made another note at that, verifying trees as viable surface.
"You see? Already you learned something. So I'm both keeping your and my end of our bet." She smiled at that. Kneeling down next to the prone ninja the girl continued her conversation as well as investigation.
"What have you tried walking on? Beside trees and this wall, I mean?" Naruto looked at her blankly, already nearly having regained his breath. "You mean nothing? Aren't you curious what the limits are?"
"Well, I've seen Kakashi-sensei walk on water…"
It was the girl's turn to look blankly at him.
"On water. Ninja can walk on water." That certainly did not resolve with her perceptions and mindset about the rules of the what-was-possible and rules of the universe at large. If everyone could theoretically learn chakra and thus walk on water, why need bridges? Wait. Carts and stuff wouldn't also roll on water when a person who could walk on water pulled one, right? That might be it…
While the girl was trying to reconcile her world view with this new knowledge, Naruto rose to his feet and held out a hand for her to do the same.
"You're okay, right?"
Still with a certain shock on her face the girl discarded a lot of her notes and speculations as 'all but confirmed', leaving her with very little in regards to the whole walking thing.
"Yeah, I'll survive." She shook her head to get in the right head space again. "Okay, that actually helps a lot. Only a few things to try out now." For the next question she looked pleadingly at Naruto. "But first, please tell me Ninja can't walk on air or something ridiculous like that!"
After giving that some thought, the ninja denied her guess. "I don't know of any flying ninja, at least. But that would be so cool! Imagine flying!"
Relaxing at that she calmed visibly down. Some modicum of respect for the laws of physics at last. Ripping a page out of her note book, she spit on one side and plastered it on the wall. It stuck to the same.
"Okay, new test. Walk on the wall, put one foot on the paper, one on the wall. No need to stand there for long."
Naruto screwed up his face "I don't want to walk in your spit!"
The girl just rolled her eyes. "Spit's on the other side, now get to it. You still want the candy, right?" She mischievously didn't tell him that she technically wasn't obligated to give him her candy anymore, since she found something he couldn't walk on: air. But why loose a source of knowledge prematurely?
Naruto obliged the instruction with a doubtful face. So far he hadn't had any reason to worry. When he stood with one foot on the paper, the girl tried to tuck it from under the foot. It didn't budge the slightest.
"Now I want you to lift this foot very softly. Ideally the page will stick to your foot." Again Naruto did as instructed, and again everything went fine. The paper stuck ever so slightly to his foot. With a soft tuck the girl was able to remove it from the sole of his foot, only to plaster it once more against the wall.
"Now, put the foot down again on the paper. But this time, stick your foot to the paper as hard as you can without sticking to the wall with that foot at the same time." After explaining once more and demonstrating with her hands what she meant Naruto to do with his feet, the ninja understood and complied.
It was successful. Somewhat. The paper at least was sticking with more force to the foot than before, but not as strongly as when Naruto actually stood on it.
"Okay, that's it, for now." At this Naruto came flipped down from the wall. "Well, there's one more thing. Could you stick to the ground, but only softly, and then lift your leg?"
Naruto wondered at the reasoning for that, but, well, thrice the charm, what's the harm, right?
Like all the times before, first Naruto moulded chakra in the bottom of his stomach and then sent it down his legs. He felt it pass through both the soles of his feet and entering the ground in a swirling motion. After solidifying the previously very liquid chakra, he pulled the energy molasses back to his feet, anchoring him to the ground. Then he reduced the chakra being funnelled to one foot until he could barely feel the feedback anymore.
Trying to lift his heel, Naruto was momentarily confused. Lifting his leg was harder than normal, until his foot came free with a jerk. Huh. Look at that. Some of the ground was sticking to the sole, parts of soil crumbling away.
He looked confused at the girl, who was smiling broadly, the broadest smile the ninja had seen on her face since they met. Whatever had happened, she enjoyed it very much.
"Yes! I guessed as much, but this confirms it!"
"What confirms what?"
"The chakra stickiness! I don't know how it works, but how it works!"
"Say what?"
"However it does what it does, it works by projecting a kind of stickiness from the soles of your feet. You can either adjust the degree of stickiness or depth of it! Remember the paper? You could stand equally well with either the foot on the paper or the one directly on the wall, right?"
Naruto nodded questioningly at that, albeit happy his new acquaintance was happy.
"The stickiness went through the paper, keeping you sticking to the wall. But then when I asked you to stick only the paper to the foot, with different degrees of stickiness, you could lift your foot off the wall and have the paper stick to to your foot! That means the stickiness was limited in depth or intensity. Or maybe both!" She excitedly continued with her observation. "But that's not all! The last bit with the ground means a lot! But I still have to think on it a bit more. There are so many possibilities! It's like manmade superglue!"
"That is great! I don't understand all, but some of it I didn't know! Do you mind if I ask Kakashi-sensei some of this stuff? If what you discovered is true, he may have some advice." At this Naruto quickly cast a few side glances around. Satisfied at not having sees another person, he leaned closer, whispering conspiratorially. "He may be reading perverted books, but he knows a lot about being a ninja. I'm sure he knows something about that!"
It was this moment Naruto realised he had yet to train with his teammates. The plan had called for them to spar one-on-one and later in a small, moderated battle royal; both to get accustomed to their techniques as well as their capabilities. Naruto just had thought about now would be the time the one-on-one would have finished and he'd need to join for the free-for-all.
"I have to train with Sakura-chan and Sasuke now. Do you mind if we call it a day?"
Waving her note book she answered, "sure, I need to put some thought into this, anyway. Tomorrow, same time and place?"
"I'll be there!" He turned to his clones helping the workers on the bridge. "Guys, it's time to train!" At this the Naruto clones roared back, somewhat simultaneously "We know!" before forming seals to dispel themselves once their immediate tasks were finished.
"Bye, Naruto!"
As he turned, Naruto stopped. He had nearly forgotten to ask her name, again!
"Hey, I forgot! What's your name?"
Laughing at that, she smiled at him. "Aoi!" Then she waved and turned her back to him, walking along the street, her mind already embroiled in the possibilities and implications of this 'chakra'.
"Kakashi-sensei!" The jounin, the highest regular rank among ninja, looked up from his recent reading. And just when the main character was about to stumble in the women's bath, to boot!
"What is it."
"Naruto is cheating!"
"I'm not!"
"You totally do!"
"Do not!"
The pink haired kunoichi, the female ninja, was of the same age and comparable height to Naruto. The both of them had been sparring, with the occasional glance by Kakashi to make note of, but not yet correct this or that error they had in their techniques. While Sakura wasn't exactly a prodigy, she had the basics down top-notch, but lacking a bit in the speed department, and being too predictable.
Naruto on the other hand was a mess. Wherever he had learned what he called techniques, the teaching had been very sloppy. Many of his stances were off kilter and to compensate he applied either too much or too little force in his jabs, kicks and throws. Sakura shouldn't have any problem dealing with him. So why was she complaining about cheating?
Sighing mentally, he put the book back into his pocket.
"What did he do?"
"He kicked dirt at my face!"
Kakashi looked pointedly at his student, who managed to look both guilty and defiant. Sakura, on the other hand, looked as if she was about be vindicated.
"Well done, Naruto." Both of them sputtered at that, one because he didn't understand, and the other due to feeling a lot of indignation. Somehow exuding calmness, Kakashi continued.
"Naruto, you did well because you thought outside of the parameters given to you. You were both sparring to improve your martial arts, but neither of you should expect the other to 'play fair'. Ninja don't play fair. Ninja play to win. To utterly defeat the enemy. If the enemy is whimpering on the ground after we beat the crap out of him, even better." Naruto was grinning hugely at the praise, only to have it wiped from his face a moment later.
"However, Naruto, this was and is a sparring match. Its goal is to improve your martial arts, which neither of you have mastered yet. Especially you, Naruto. Sakura, you will perform the movements of techniques. Naruto will observe," Sakura was about to protest, she did not want to give Naruto any sanctioned reason to stare at her, but was mollified by the continued explanation. "And he will repeat your moves. If he does so badly, you can correct him." Sakura did not miss the leeway this instruction gave her in methods to 'correct' the brat.
"By the way, where did you come up with dirt? The ground is pretty solid here and Sakura didn't fall at any point for you to kick sand in her face."
"It's easier to show, okay?" At that Naruto simply lifted his foot jerkily with a bit of condensed ground sticking to the sole.
"Your shoes are spiked? That can be dangerous, especially of your sparring partner doesn't know that."
"No!" With a bit of indignation evident on his face, he stopped the chakra flowing to his foot completely, which let the lifted earth instantly fall to the ground. "See, no spikes."
"Wait. You lifted the ground with your chakra? How did you come up with that?"
A bit awkwardly Naruto admitted, "I didn't, a… friend did."
At that Kakashi narrowed his only visible eye suspiciously. The other was occluded by a strap of cloth that held a metal plate. Etched in that plate was the symbol of their village, Hidden Leaf. Thus, he had only one left to look at them.
"A friend. You don't say…" He then relaxed outwardly again, giving the two of them the appearance and go-ahead to continue with their match, but this time only with the agreed upon moves. Sakura was soon enough exasperatedly correcting Naruto's wrong stances and movements, and quite a few times unable to refrain from punching him. Kakashi on the other hand was both intrigued and worried. 'A friend, he says, a friend comes up with such an oblique application of simple walking is a 'friend' I certainly need to keep an eye on…'
Note: I don't know where this will lead to, but don't expect a lot of updates, or at least not a lot of story. This is mere mutated bunny repeatedly screaming "KANEDA!" at me. I think it will go into scenes of the manga (or anime) I remember and give Naruto some new unexpected moves, and his opponents reactions to the same freaky techniques, but the overall plot will essentially be the same. And I'll definitely stick to before the time skip.