I don't own Naruto.
Two Weeks Later
BOOM
"You think you can move like a snake? First you have to think like a snake. Now die!"
CRASH
"Hiding behind a tree won't work. I can smell you, pinky!"
SLICE
"Oh, you've moved? More's the pity."
CLANG
Anko drew a kunai and crossed blades with Sakura, who had leapt from a tree, intent on stabbing the snake summoner with her knife. The pinkette moved to lift up her slanted headband, but Anko weaved around her blade and bashed her to the ground.
"Impressive attempt. And you didn't even react to my taunting; so there's improvement there. But I do not want to see you using that pink eye of yours. You barely have the chakra to survive a minute of it and I don't want to be responsible if you die of chakra exhaustion. If you die of poisoning, however... Oh, at least you're following the rest of my teaching to the letter. That other idiot thinks he knows better."
"I can hear you, you know!"
"Why do you think I'm saying it?"
Naruto scowled, standing from his position off to the side and walking over to the two kunoichi.
"I don't care what you say, I'm nearly there. Look at my leaf!"
He thrust a healthy green leaf into Anko's face, causing her to slap it away on reflex and let it flutter into a nearby pile of leaves.
"No! How am I meant to train now? But you saw it though, right? The leaf? It crumpled!"
"It was a leaf. A normal sized leaf."
"Aha - that's where you're wrong. It began as a larger-than-average leaf that I crumpled. I made it slightly smaller. I'm nearly there!"
Sakura, having been excused from the conversation, decided to speak up.
"Naru-to! What the hell are you trying to do?"
"The brat thinks that elemental affinities are for sissies. So he's trying to learn to use all five elements. That was his lightning training in progress."
"I managed to stop a leaf from burning! And I made another go withered and flaky. Granted, I'm not all the way there but-"
"You didn't put your leaf anywhere near the candle flame!" Anko interrupted. "And the other leaf withered because you kept it for a week and it dried out!"
"Everyone's a critic…" the blond mumbled.
"Yes, because you're an idiot! You already have two nature affinities, and they're two of the rarer and more versatile elements for this country. So why are you being so greedy?"
"Jiji's book says that anyone can learn techniques from any element and master them if they have the time and skill. I'm just taking it slowly because no-one will teach me exercises for fire, earth or lightning."
"That's because you're a genin, and no right-minded jōnin would teach you anything about nature transformation right now."
"Kakashi-sensei taught me! And he'd have taught Sakura if she wasn't moping on the way back."
"I wasn't moping; I was upset!" Sakura argued. "And I had every reason to mope."
"Moping aside," Anko said. "Kakashi wasn't in his right mind. That's why he was sent away. Hopefully he won't be away with the fairies anymore when he returns."
"Was that a gay joke at my expense, Anko-san?" asked a familiar voice. "I'll have you know that Gai is eccentric, but he's in no way homosexual. And you know better than anyone that I'm as straight as they come."
"Stop wiggling your eyebrows, Kakashi, it was one drink, that you were late for, and it ended up in your face. And 'away with the fairies' is a normal, non-sexuality-related phrase. Stop foisting your homophobia onto me."
"Um, oka-"
"Sensei!" Naruto shouted. "Look at my leaf!"
The cyclops took the proffered leaf.
"Um, Naruto, this is a regular leaf. I heard Anko had trained you these past few weeks, but she didn't beat you hard enough to give you amnesia, did she? You could cut through a leaf the day after we left Wave."
"Oh, er, sorry. This is the wrong leaf." Naruto took it back and rubbed his head, laughing nervously. "Still, good to see you back. Sakura was getting worried."
"I was- Ugh. Naruto's been a pain, sensei. You need to teach him something, fast. Anko's restricted herself to taijutsu and he's been driving us crazy because of it."
Kakashi eye-smiled and ruffled Sakura's hair.
"Well then there's good news for you. I'm no longer in disgrace, not entirely, and the Hokage has approved me taking you on a training trip. The council were angry at him for giving you Sasuke's eyes without putting it past them, but now they're transplanted they don't want you going out on missions until you're ready to defend yourselves. That means me taking you training, somewhere far away from A-rank missing-nins or anything like that."
"But where could that be? Every nation has deserters," Sakura chimed.
"Not here, I can assure you." Kakashi rolled up his sleeve, bit his thumb, and rubbed some of the blood along a tattoo. "I need you to sign this."
A large scroll, about forearm-length, appeared in a puff of smoke, and Kakashi laid it out on the grass.
"Ooh-hoo, you're in for a treat, kiddies," Anko smirked.
"This is the Hatake family summoning contract. You've seen my nin-dogs before - well, now we're going to stay with them for a while."
Anko raised an eyebrow.
"Well nobody'll think to look there, I'll give you that."
Their sensei rolled out the scroll until they could see blank lines. Hatake Kakashi's name was proudly displayed there, with Hatake Sakumo's faded-out signature further up, and other faded names stretching even further.
"You need to cut a finger and sign here. This will allow you to summon dogs and, more importantly, be reverse-summoned by them."
"Why would we-" Sakura started. "Oh, I see. Now that makes sense."
"What makes sense?" Naruto asked. "Where would we go?"
"Summons don't live in this dimension, Naruto," Sakura explained. "It's somewhere else, with the different countries split by the creatures that live there rather than the elements. The only known way to get there is by the summoning technique in conjunction with a summoning contract, so very few people would be able to get there."
"But I'm one of 'em!" Anko said. "So stay sharp, 'cause Auntie Anko might pop in to see how you're doing at some point."
"Oh god no!" Naruto shouted."Anything but that!"
As Anko chased Naruto around, Sakura calmly made a cut on her forefinger and wrote her name on the contract. A glow of chakra confirmed the signature and Kakashi called over to Anko. She dragged over a trussed-up Naruto, who was glowering at the snakes binding him.
"You know I can escape," he taunted.
"Yesssss, but we got our revennnge, didn'ttt we?" one of the snakes hissed in reply.
Paling slightly, the jinchūriki bit his finger and started to write his name. Partway through the 'k' of 'Uzumaki', his finger healed and he had to bite down again.
"Excellent," Kakashi said. "Now we can begin. Summoning Technique!"
The jōnin slammed his hand to the ground and summoned a single nin-dog. Pakkun emerged from the smoke and greeted them with a raised paw.
"Yo."
"Pakkun, the kids have signed the contract. Can you head back and get the alpha to summon us to the forest?"
"Hai." The summon disappeared as quickly as he'd arrived.
"Now you won't have experienced this before," Kakashi said. "And it may feel a little disorienting. Just rem-"
He was interrupted by the fact that he'd burst into smoke, shortly followed by the two genin.
Naruto felt a gently-increasing pressure on all sides and could see a swirling vacuum of smoke with the sensation of motion. After less than a second, the pressure disappeared, and he was standing under the shade of a canopy in a forest with towering trees.
"Welcome, pups," came a growling voice from the side. Two fallen trees were leaning together to create a shadowed enclosure and a large dog slowly padded over to them. "I am Inuka, alpha of the dog pack. You may have signed the summoning scroll, but you must first face my test if you wish to be a fully-fledged dog summoner. Your sensei never passed this test, which is why he can only summon the one smaller nin-dog pack."
The dog had white fur and looked more like a wolf than a dog. It reached higher than Kakashi and prowled with grace, as though not a single movement was wasted.
"You!" It growled, lashing out a paw at Sakura and only stopping before he would've struck her in the face. She remained motionless, barely reacting to the threat. "You… may have what it takes. You have bravery. But do you have lo-"
The alpha was interrupted when Sakura, curious, felt the padding of the paw still hovering near her face.
"So soft…" she murmured.
The intimidating dog fell to his haunches, goofy grin on his face, and looked to the side coyly.
"Well, I do put a lot of effort into keeping them soft… Don't think this means I like you! But still, I suppose I'll let the two of you summon us without the test. Because you're… obviously ninja of good taste."
Kakashi facefaulted. He'd tried in vain to be able to summon the larger dogs several times along the years, but had failed their stringent tests every time. Apparently they held the fact that he'd once tried to prioritise the mission over the health of his teammates as the worst crime possible, and still didn't think he'd been in penance for long enough. The nin-dogs were fanatical about pack loyalty, something he'd only started to understand as he grew older.
"So what are we going to do here, sensei?" Naruto asked.
"We're going to be training as a team, of course," Kakashi said, smiling behind his mask.
"But how can we be a team with just the three of us? Doesn't Konoha have to have four-man cells for genin teams?" Sakura asked.
"Ma, we'll sort that out. And, for now, I'm going to be teaching you about the Sharingan. In our first months together I didn't teach you directly. I put you through team bonding exercises, because they were the fastest way to improve your combat efficiency and village loyalty. I'm sorry if that made you feel like I was ignoring you." The jōnin glanced at Naruto. "But I've been cataloguing your skills and I've made a training plan.
Sakura. You have excellent chakra control. You have already demonstrated the ability to channel chakra through your limbs to enhance punches. Unfortunately you've so far only used that skill unconsciously to hit Naruto."
The pinkette sent an apologetic look to Naruto.
"As such I will be training you first in genjutsu and healing techniques to exploit your control. As we work we will increase your chakra reserves to allow you better and more sustained use of the Sharingan."
The girl nodded, idly fingering the forehead protector that was slanted over her eye, much like her sensei.
"Naruto. You have changed remarkably since our mission in Wave. I must commend you. Previously your chakra control was awful, although we know that wasn't your fault, your taijutsu sloppy, ninjutsu wasteful, genjutsu non-existent. You were a brawler and a front line tank, hardly an ideal ninja role. But you've improved across the board. Both of you, in fact, flourished under Mitarashi-san's tutelage. So Naruto, I will focus on developing your ninjutsu skills and introducing you to fūinjutsu. You in particular will want to understand this art."
Naruto nodded resolutely, reflexively glancing down to his stomach. Sakura looked interested at the interplay between the two, but was unable to grasp its significance.
"In addition, I will tell you the known history of the Sharingan, and how it develops over time.
There are three tomoe to the average Sharingan, and they are unlocked when their carrier is exposed to great stress. Typically this happens in battle when a ninja is put in a life-or-death situation. Blood and adrenaline flood the eyes and trigger a response from the genetic code; nearly instantaneous evolution. But that isn't the final stage. There is a further level to the Sharingan. The Mangekyo Sharingan. The key to unlocking it is guilt... The grief of being responsible for the death of somebody close to you. It has to be fresh and raw for the evolution to happen. That was one of the factors argued in favour of giving you those eyes; your grief is still strong and I believe you will develop the Mangekyo. These eyes are even more dangerous than ever - they can manipulate the very nature of reality."
"But sensei," Naruto asked. "Doesn't that seem a little overpowered? They're already a scarily dangerous tool, but they can change reality? Why are they mostly gone, in that case?"
"Unlocking the Mangekyo Sharingan was a secret, even to many in the clan. Because the Uchiha were an insular people, partly due to the suspicions of the Second Hokage, the elders didn't want their clansmen killing each other for power. It does seem overpowered. It is. But using the Mangekyo Sharingan degrades the eye. It simply requires too much blood and chakra to flow through the eyes, eventually causing blindness."
"Do you have the Mangekyo Sharingan, sensei?"
The cyclopean jōnin looked off into the distance before replying.
"Yes, I do. And that's one of the reasons I'm uniquely qualified to teach you about it.
Now Sakura, uncover your eye. I'm going to perform a jutsu and you're going to watch."
Sakura flipped up her headband, with Naruto not needing to bother. Kakashi lazily tossed a kunai at a tree before flipping through some handseals.
"Kunai shadow clone technique!"
The kunai became dozens and peppered the tree. After a few seconds the copies disappeared, leaving the original lodged in the tree, with stab marks arranged around it.
"Now I'm not comfortable with you using the regular shadow clone technique, Sakura, because you don't have enough chakra for it. But the extent of this technique is defined by the amount of chakra you choose to put in. Now, I want to see both of you try the technique with the same amount of chakra I did."
Both genin hopped to their feet, Sakura covering her eye again. They repeated the technique and replicated the number of flying kunai exactly.
As the shadow cloned kunai disappeared, Kakashi observed his students.
"Now, did you notice any drawbacks?"
"I had to concentrate to remember the handseals," Naruto said. "I ran through them automatically, so I had to watch my hands to remember the handseals. I did that, so now I know a bit more about how it works, but if I hadn't then I wouldn't know how to adapt the technique for different circumstances."
"That's right, Naruto. Sakura?"
"I... I knew the handseals. And I knew how it worked."
Kakashi's eye widened.
"Do you know how that is? That could be a terribly effective skill if it can be replicated."
Sakura shook her head nervously, the evasiveness not lost on Kakashi. Sakura wasn't going to tell him that Inner Sakura had helpfully told her all about the technique she'd just seen, just like she normally did with any information Sakura couldn't consciously remember.
"So, barring Sakura's surprising talent, it seems that was a success. But it is always advisable to train with techniques before trying to use them again in battle - you'll learn better how and when to use them. Now, as for handseals-"
"Doesn't the Sharingan only work on techniques when the other ninja uses the full sequence of handseals? I read that, with training, you can cut down on the amount of handseals needed, and sometimes not have to use them at all," Naruto said.
"That's true, Naruto, but as the Sharingan progresses to later stages, it becomes better able to puzzle out the gaps between handseals. Of course, when you then reproduce the technique you have to use the full sequence, which just makes training the more useful. Where did you read that? I wasn't aware you were much interested in books."
"Yeah, Naruto," Sakura added. "I thought you were more into physical training."
"I read it in a book that jiji gave to me. He said it was how he trained when he was a genin."
"Sarutobi-sama's training guide? Isn't that a little advanced for... No, he was right to give it to you. He must have a great deal of faith in you. Many ninja have read that book but few have the time to actually take those words into practice. Have you read the part on elemental combination jutsu?"
"Yes, and I didn't understand it. How can you have two types of elemental chakra in your tenketsu at any one time, on top of normal chakra?"
"The Hokage didn't write that down in the book, and for good reason. It was one of his prized chakra manipulation techniques; one of the reasons a shinobi with no bloodline could go toe to toe with the lava or dust release shinobi of Iwa. But Sarutobi taught his students, Jiraiya taught Minato-sensei, and he taught me. He folds his chakra back on itself while in the tenketsu, increasing its density and leaving space for more chakra to occupy it. This can put immense strain on the chakra network and isn't something to be taken lightly. I was never very good at it. Naruto, you might as well try it due to the size of your tenketsu. Sakura, we'll work on other things before getting to that."
The two genin nodded.
"So what now, sensei?" Sakura asked.
Kakashi dangled a bell in front of his two students and smiled.
"You remember this, don't you?"
They groaned.
"But this time there's no trick to it. The person with the bell gets dinner, the other goes hungry. Start!"
After two months in the summons' dimension, Naruto and Sakura were completely different to the genin they had been before. Sparring for the bells every evening had taught them how to deal with high-speed enemies, and their ability to track movement with both eyes at the same time was back to normal. Despite whomever got the bell by evening, it had become a tradition for the two genin to share anyway, leading Kakashi to cave a little and make the evening meal extra large.
Just as soon as the two genin thought they'd become able to predict where Kakashi was going to move to, he would switch styles and annihilate them. He had a bewildering arsenal of taijutsu styles memorised and, consequentially, so did they now. Even had Kakashi just used one style, he could use his Sharingan to predict how they would predict his movements - that kind of feedback loop meant that the faster shinobi still won every time.
Naruto and Sakura had immediately got on well with the dog clan - Naruto's boisterous nature and Sakura's calm and complimentary manner had inured them to all of the dogs, not just the clan chief.
Sakura had befriended a feisty young pup called Taruko, while Naruto had decided he wanted a companion as well and had taken to bugging Taruko's sister Harumi, who seemed to want nothing to do with the hyperactive blond. The dynamic between the blond and Harumi reminded Sakura of her early relationship with Naruto, but Harumi preferred to run away from Naruto and hadn't yet bopped him on the head.
It was the afternoon and Naruto was trying to find Harumi.
"Ne, Harumi-chan, are you sure you don't want to be my personal summon? I'll give you plenty of ramen!"
"Ramen? How disgusting! Never!"
A bush rustled as the small dog involuntarily blurted out an insult to Naruto's favourite food.
"You don't like ramen? Then you've clearly never tried enough of it! Come here and I'll take you for some."
"Agh!"
The two chased each other around the boundaries of the forest for a few hours, Harumi eventually starting to enjoy herself when she turned the tables on Naruto.
He ran, laughing, and started to pump chakra through his body, accelerating madly. After around five minutes of sprinting at top speed, he stopped to see how his pursuer was doing.
"Harumi?"
He'd just left the forest, and he could now see mountains stretching off into the distance, with a canyon fed by a river not too far away.
She wouldn't have left the forest, so Naruto moved to go back.
"What do you think you're doing here, young man?"
Naruto looked around for the source of the voice, to no success.
"Down here!"
WHACK.
Something collided with his shin, causing the blond to jump back and look down.
A small purple toad with permed hair and a basket of mushrooms was glaring at him.
"Kids these days, always running around fast and never looking down. What's your name, boy?"
"Um, Uzumaki Naruto, ma'am."
The old toad hmmed to herself.
"Well, at least he can be trained," she muttered. "You need to come with me! Trespassing on Mount Myobuku is a serious offence. Are you a dog summoner?"
"H-Hai, I am, but I wandered here by accident. I didn't know this was toad territory."
"That may gain you some leniency, but the dogs clearly... mark their territory and, as a summoner, you should have been able to determine the limits. Either they haven't trained you effectively, or you're here in bad faith. Either way, our clans have a problem. Follow me."
The elder toad hopped down into the gorge, Naruto running down the cliff face as she jumped from outcrop to outcrop. When they landed, they followed the river deeper into the mountainous territory, following a valley's interlocking spurs until Naruto wasn't quite sure of his location. Eventually, the valley opened to a huge lake, surrounded by mountains and toad statues.
"This waterfall is the domain of the Elder Toad Sage," the brusque toad said. "He will see you in his own time. Wait here."
With that, she hopped off across the water, leaving Naruto alone at the side of a lake. The waterfall fed into a small pool of water, but as he looked closer it became apparent that what was flowing wasn't water - it was something darker and more viscous. He leant over to dip a finger in the strange substance, but the ground shook with a sudden tremor and Naruto fell in head-first.
"Gamahiro, what have you done with my sake?" a distant voice boomed, as the tremors abated, clearly as a very large toad hopped away.
As the tremors began to subside, Naruto realised that he could still feel the being's chakra as it moved away. The toad had a massive chakra presence, but
it flowed and eddied gently, like water or curling smoke. It was attuned to the environment around it, and Naruto moved on from feeling the toad's chakra to feeling the chakra that permeated the atmosphere. As he concentrated, he could feel the chakra start to flow into him, until-
"Damn fool child!"
A sticky tongue wrapped around his midriff and hurled him out of the pond. Naruto landed on his head but, strangely, was none the worse for it. He moved to stand up but his right leg flopped uselessly as he put weight on it.
"Argh! My leg!"
His leg had turned into some sort of frog leg, having elongated and thinned.
"Webbed toes!" he wailed.
"Oh, come here, fool child, it's not so bad," the stranger crooned.
WHACK
Naruto nursed his head, the only thing he could do after being struck in the head with a stick.
"Hey, what do y- oh, my leg!"
"Baka. Why were you in the toad oil fountain? You do know that's a sacred monument of Myobuku, don't you? And trying to draw in nature chakra at your age? Sheer idiocy."
"Was that what that feeling was?" Naruto asked.
The toad sighed.
"Yes, you just experienced sage mode, where you balance your chakra with nature and become one with it. Very briefly, you did. I'm glad Ma told me to keep an eye on you; you'd have been like them if you'd been in sage mode any longer."
He pointed at the toad statues circling the lake and frowned at the young boy.
"Each of those statues was a person once. If you lose focus when entering sage mode, the nature energy is unbalanced and you turn into stone. You humans also turn into toads when you try it. These statues are a grim reminder to take caution, and monuments to honour their bravery. You nearly joined their ranks, or would've if we hadn't decided to deliver your granite corpse back where you came from."
A rumble emerged from a nearby cavern.
"That is the Elder Toad Sage," the toad mumbled. "Be polite and answer his questions."
A pressure emerged from the cavern mouth and pressed down on both boy and toad, increasing as the Elder moved ever closer. Just as the pressure reached its peak, the Elder came into view.
"Ah, Pa, are you here to deliver the worms? I've finished all mine already."
"Ah, no, venerable Elder, I bring you this human. He trespassed on our land and Ma brought him here."
"Ah, Uzumaki Naruto," the sage grumbled. "It is nice to finally meet the Child of Prophesy."
Pa looked mortified and tried to settle the meeting.
"Well, this was nice, but I suppose I'll take you back to th-"
"Has Jiraiya brought you here? I always thought he'd bring his pupil's son here, but I didn't foresee it being this soon. Are you here for the Key?"
"What key? The Toad Sannin? And he trained my father?"
Pa groaned and slapped his head, finally losing his temper.
"It wasn't meant to work like this! You were meant to say something vague about him having great promise and then tell him to seek out Jiraiya-child. Why did you have to say all of that?"
"Oh, what was that?" the Sage asked. "I hear something in my cave. I'll be off now."
With that, the ancient elder hopped away, leaving a very confused Naruto with a very annoyed Pa.
"What was all that about? Should we be following him?"
"That was- no, no it's fine," Pa said. "We knew you would come here one day because of the burden you carry, but also because Jiraiya would take you on as his apprentice. You wandered here by chance and we thought we could speed up that process. The Elder Sage just put all that planning to ruins. Here's some advice - ninja need to understand subterfuge. Don't go blowing secrets like that future-addled geezer!"
The toad calmed down and collected himself.
"Okay, here's what you are going to do. When you return to Konoha you are going to find Jiraiya of the Sannin and tell him that Pa says you're ready. We'd summon him here now but he's probably off doing something delicate for his village. I'll see you again when he thinks you're ready to begin sage training."
"Wait, isn't there some sort of test like the dogs had to allow me back here?"
"Normally, yes, but we can't really afford not to have you as a summoner. Bunta might give you a token test but that's just because he's headstrong. Just go back to the dogs and finish your training. Nobody's angry with you; Ma just used that as a pretext to drag you here. I look forward to seeing you again."
Naruto set off on the winding path back to the forest before he remembered to ask.
"Wait, who was my father?"
Pa had already disappeared, leaving Naruto to trudge back alone, questions unanswered.
"So if I use a triangle rather than a circle, then I can-"
"No, stick to the circle. Do you remember what happened last time you tried a different shape?"
Naruto shrugged.
"It was an experiment. Shadow clones are low risk guinea pigs."
"Somebody else could have been caught in the blast!" Kakashi interjected. "Fuinjutsu is not a forgiving art, and you need to slow down before you put others at risk."
"Ma, sensei, have I not advanced enough to go beyond the baby stuff? Fuinjutsu isn't that difficult; you just need to remember a lot and pay close attention."
Kakashi grunted, peering at the boy.
"If it's so easy to remember, then talk me through the basics again."
Naruto groaned.
"Sealing is the art of storing and directing chakra for different effects. Ninja handseals are a limited way of replicating this process, but there's only so many different poses the human hands can go through; whereas the possibilities for written fuinjutsu are endless.
One major distinction made in the art is between inputs, processes and output. Inputs are usually chakra, ink, or chakra-infused substances like treated ink or blood. Processes are the internal mechanics of the seal, and are further divided into categories. The outputs are varied and depend wholly on the processes, but ninja usually work backwards from the output they want when they design a seal.
Processes can be divided into the main headings of chakra filtration, storage, expression, logistical and otherly.
Chakra filtering seals change chakra from one form to another - pure to elemental, demonic to human, yin to yang.
Storage seals use space-time folding to store objects as intangible chakra constructs.
Expression seals direct chakra into noticeable effects like explosions or smoke. If you've sealed something away, you need an expression seal in order to bring it back into reality again.
Logistical seals direct where and how the other types of seal will work. If you store a kunai in a seal on your wrist, logistical seals make sure the kunai appears in your hand and not embedded in your arm.
Otherly seals stretch the limits of human sealing knowledge. This contains advanced time-space work and contracts with summons races or other beings.
Many seals have parts from all types of seal to function. An expression seal to convert excess chakra into smoke is quite common, otherwise the seal would overload and could become dangerous. Logistical seals can also be used to determine how different seals react with each other.
Seals are written in kanji, but have to be structured using geometric shape principles or the chakra won't flow properly. The most stable shape is the circle, but it is also the least versatile. The fewer edges a shape has, the more difficult it is to use. Then there are advanced shapes such as seals forming other words that can in turn be used as seals, or spirals.
These shapes interact at a macro scale, and most seals are defined by the amount of shapes they have. The more there are, the more stable the seal. Some sealing masters have superstitions about certain numbers, like the Fourth Hokage, who only ever used even numbers..."
"Well that wasn't entirely superstition, Naruto," Kakashi interjected. "The Fourth always liked to build redundancies into his work, so he'd double the number he was already using. Your seal, for example, is eight trigrams. He would've only needed two trigrams to seal the Kyuubi - but he created four backups of his work to account for how corrosive the demon chakra is."
"Okay, well, do I have to say any more? You know that I get it, right?"
"I suppose. Now how is your work on channelling lightning going?"
"Not great. I'm doing fine with earth and fire, but lightning's escaping me for some reason. I can't get any further than the leaf crumpling exercise."
"Well that isn't unexpected. Lightning is between wind and water, your primary affinities, so you're having the hardest time with it. Many shinobi devote their lives to developing only a second element and fail, so don't beat yourself up about it. Hopefully that will be enough chakra for you to be able to use the five-element seal."
"Is it really that useful, sensei?"
"Of course it is. You inject five different types of chakra into an opponent's body and cause chakra arryhthmia. Unless they have all five affinities, and strongly, too, it will interrupt their chakra control and make them all but useless in battle. Now, concentrate on your calligraphy training while I go and check on Sakura."
Naruto held in a groan and Kakashi wandered off.
He walked away from the young jinchūrikki and along the banks of a river to find his female student. Naruto had been coming on dangerously fast. When he concentrated and stopped joking around, he was the spitting image of his father, in both looks and personality. After the incident with the toads, Kakashi had no doubts that Naruto would go far, particularly as he was apparently slated to become Jiraiya's apprentice. It was his other student that worried him. She had come a long way too. She absorbed information like a sponge - far faster than Naruto could. But her problems lay in application. He could teach her a genjutsu and she could perform it perfectly after a few tries, but her chakra reserves and bodily strength was still pitifully low. She had stopped eating like an ant and started exercising, but it appeared that she was simply not genetically disposed to building high amounts of muscle. It wasn't entirely surprising, seeing as she came from a civilian family, but it was depressing. Naruto was surpassing her completely and it was causing tensions in the team.
He turned a bend in the river so find Sakura balanced in the middle, jogging upstream so slowly that she was running in place. He could see the sweat beading on her brow as she exerted all the effort she could, but eventually she lapsed, her chakra ran out, and she plunged below the surface. Kakashi quickly darted under and fished her out, pulling her to the bank and making sure she was awake. If he couldn't solve the Sakura problem, his team would fall apart all over again.
Naruto was gnawing away on some small woodland creature, while Kakashi and Sakura sat around the campfire, looking a bit more reserved. Kakashi had managed to finish his meal in an instant without taking off his mask, and Sakura was worrying her food. Naruto put down the stripped bone and smiled at his teammate.
"Doesn't taste as nice as when you win, Sakura-chan, but it was still really good. Thanks, sensei! Not as good as ramen, though..." he muttered.
"Ne, Naruto, can I talk to you?" Sakura asked.
"Of course you can. Why'd you ask?"
"No, I mean alone." She gave Kakashi a beseeching glance and the jonin made himself scarce.
"Naruto..." she began. "Have you noticed how you're winning the bell test competitions every night now? It's been a few weeks and I haven't won once."
"Oh, I'm sorry, but you know you'd hate it if I tried to let you win. You know how lucky I am. Remember that random hit on sensei with the mud bullet? Lucky stuff like that seems to be happening more often. I'm just on a lucky streak - you'll get one soon too, believe it!"
"Naruto, that isn't luck. That's you getting more and more skilled. You can use four elements now, of course sensei is going to have trouble keeping up. And now that you can use that chakra folding thing, you've started being able to get him with collaboration jutsu. I can't compete with that."
It was true. Naruto had discovered that, with chakra folding, he could store multiple types of chakra in his tenketsu. If he released them at once, they could combine to make different effects. Mixing fire with earth made for rivers of scalding mud, or fire with water made a steam that could rip the bark off trees and superboil the sap inside. He'd never tried it on a human, though.
"So I'm picking up the training faster than you? There's a first time for everything, Sakura. Maybe you just need to be more patient."
"I am being patient, Naruto, but we've been here nearly three months and I can feel hardly any improvement! I can cast genjutsu and use healing techniques, but I still barely have the chakra to use them consistently or the strength to last in a prolonged battle."
"I… hell, I don't know. What do we do?"
Unbeknownst to them, Kakashi had been listening in, and he shared the same fears as his students. He'd come up with a few ideas, but nothing that could-
"Maybe I could make a seal," Naruto blurted out.
Both Kakashi and Sakura stared at him. Kakashi knew that Naruto was capable with seals, but Sakura only knew about the exploding notes and storage seals Naruto had been making.
"A seal? How will that help? It's not like an explosive note or storage seal will help me," she replied.
"A storage seal might work. I could store some of my chakra in a seal, apply it to you, and then have it inject chakra into your system. The extra stress on your tenketsu would widen them, prompting your body to create more of its own chakra. It would hurt, but it might work."
"How would something like that even work? It would probably just make my chakra points explode. It's never been done before."
"Not true, Sakura. It has been done before. In fact, that's the reason I have so much chakra."
Sakura stood up in shock and started pacing.
"You mean you've had this way of getting stronger all along and not told me? Thanks a lot, Naruto, that was really helpful."
"The seal was applied when I was a baby, and I've only just come to understand it. And there's another reason I've been hesitant to tell you…" Naruto trailed off.
In the bushes, Kakashi looked on solemnly. He was going to need to intervene if things went sour soon.
"Do you remember the stories of the Kyūbi and how it was defeated?"
Sakura looked at Naruto with a patronising expression.
"Who exactly do you think you're talking to?"
"Then you should know that it doesn't make sense. Bijū are made of chakra. Even if they're destroyed, they just reform a few years later."
"I assumed that the Fourth sealed it in another dimension or something with his Flying Thunder God technique."
"He did seal it away. But in the only place he could. In a newborn child."
Sakura stared at him with open eyes as everything started to fall into place. The sour looks from the villagers, her mother's warnings when she was a child, Naruto's birthday, the foul chakra that she'd felt on the bridge…
"You?" she stated, more than asked.
"Yeah, me," Naruto said. "The Kyūbi was sealed inside me when I was a child. That's why I have so much chakra. Maybe that's why a seal might work for you."
"Then you-" Memories of the boy's days in the Academy flashed back to her, as she realised that all the scorn she had thought he had deserved was due to other reasons. She hurtled past the fire and wrapped Naruto up in her arms, cradling his head and rocking him back and forth.
"I'm so sorry…" she muttered.
Out of earshot, Kakashi relaxed and stood down from attention. He'd been ready to intervene had Sakura taken things the wrong way. He knew that she'd lost her father in the Kyūbi attack, and could have made the wrong assumptions.
Naruto had his head pressed against her undeveloped chest, and could feel the tears trickling down the back of his neck. After a point in his childhood, Naruto had accepted that nobody would ever feel sorry for his lot in life, and had resolved not to feel sorry for himself, either. He didn't need this. But, as she rocked back and forth, shedding tears over the cruelty of children, Naruto realised that Sakura needed the comfort more than he did. He wrapped his arms around her and reciprocated the hug, ignoring the painful pressure on his neck as she clutched him tighter.
Kakashi gave a wan smile as he gazed at his students. He'd need to keep an eye out on Naruto when he started developing that seal for Sakura, but this interaction had taken a weight off his mind. His fears of having another team fall apart seemed unfounded, at least for now.
AN: Time to respond to reviews. Seeing as I have so few at the moment (cough), I can comfortably reply to all of them. So here are my responses to all both of them.
Kamen Rider Extreme: I've already written about 50,000 words of this fic and can tell you that I currently don't intend for the physical element of chakra to be used like KI, or for the spiritual element to be used like reiatsu. But there is a timeskip in which plenty of things happen, so I may factor this idea in after that. Thanks. Honestly, the name is the thing I put the least amount of time into and I will probably change it again to something a little more fitting and original. I got to 50,000 with 'untitled project' so clearly I need to have a think.
GeassDragon: You're right that Sakura wasn't ready for the Sharingan eye when it was given to her. I don't believe that it requires so much chakra that uncovering it briefly would kill her, but I take your point. The Hokage thought that the possibility of her obtaining the Mangekyo Sharingan outweighed the costs of her death. That, and he was confident that she could train up her chakra reserves when Anko wasn't training them, and he was unsure whether Naruto would accept the eye if Sakura didn't get the other. He's a real stickler for his idea of fairness and Hiruzen knew that a jinchūriki with a Mangekyo Sharingan would be unstoppable. At this point in the fic Sakura can manage about a minute with her eye uncovered before being at serious risk. Sakura's primary role in the manga is as a healer, but I don't think a genjutsu specialism is too far removed from that, with her perfect control, and Itachi has shown that a genjutsu-using Sharingan wielder is terrifying.