It had started with a trip to Suna. Naruto wouldn't have been brought along if not for a combination of problems with the boy's guard right before the trip, and Hiruzen hadn't trusted said guard to behave while he was away. So Naruto had been dragged along while a new set of guards was vetted by those Hiruzen personally trusted. Jiraiya had somehow found out about the change in plans and shown up along the route to Suna and joined them. Hiruzen had been annoyed by that, up until his former student had found extra seals on Naruto.
There would be a reckoning when they returned to the village.
The rest of the trip had been going well enough, Jiraiya watching Naruto while Hiruzen dealt with the diplomatic issues. Until the two ran into Rasa's youngest son and Jiraiya had subsequently stormed into a meeting to insist that the Suna jinchūriki's seal be repaired before it "released the beast or converted its chakra into a continent-busting suicide explosion." Rasa had initially looked furious at the interruption, worried about the 'release' comment, and then paled in terror at the 'explosion' comment. He was in good company on the latter, as Hiruzen had joined him.
Within three days the updated treaty terms between the two villages had been confirmed, Gaara had his seal repaired and had taken to sleeping to the point that he could be mistaken for a relative of the Nara, and Rasa found himself needing to provide something as an exchange for the help. Of course, being the Kazekage meant that his own information network had informed him about Naruto's burden, and he proposed an interesting repayment.
Thus it ended up that they left Suna with young Naruto carrying a sealing scroll. One containing a fox puppet, instructions on basic maintenance, and basic puppetry techniques. Amusingly, Hiruzen knew that Rasa had tried to pull a fast one, as the fox puppet was one that no Suna puppeteer had been able to make work ever since a previous user had gone up against an Uzumaki. One that had placed seals on the puppet to prevent all non-Uzumakis from using it, and Rasa apparently didn't know that Naruto's name wasn't 'in memory of' as many had assumed.
Well, either that or the Kazekage was getting soft and actually honored the deal as presented, knowing that Naruto would be able to use the puppet when his own people had never been able to. Hiruzen didn't think that likely.
Naruto took to learning about how to control the puppet incredibly well, once he'd learned to read the scrolls anyway. He'd also started looking into sealing, both to ensure he could carry the puppet and other supplies with him and because Jiraiya had pointed out that the proper use of seals could make the puppet a whole lot more effective. One might think that this would eventually result in less pranks being played by the boy, with so much focus on other things, but he used what he was learning to play much more involved pranks instead.
Being able to trigger devices and traps with chakra strings as he ran past them, instead of relying on normal tripwires, made him a lot more interesting to chase. The academy instructors came to hate that he could hide things days in advance and then trigger them when he wanted to as well, and that was all before he finally got sealing basics down. There he proved to be a true Uzumaki, unable to tell that there was a box he was supposed to be working within.
He used the money he made from selling chakra string tripwire tags to the ANBU to purchase supplies and tools he needed to work on the fox puppet, and eventually to start building his own non-fox puppets. The villagers were incredibly likely to attack the fox puppet on sight, but the other smaller puppets he made to learn what he was doing were largely left alone by comparison. At least until he started using them in pranks, with the Hyuuga being the only ones that he had to be careful around. They could see and break the chakra strings, which annoyed Naruto greatly.
Sadly, none of the skills he picked up helped him in the academy. Puppeteering wasn't considered a valid alternative skill in the Konoha curriculum, nor was sealing. He still couldn't do the normal clone, and eventually failed the exam. But Mizuki had approached him about an alternative exam, which had led to Naruto getting the Scroll of Seals out of the Hokage residence. Which he'd pulled off by sealing it into one of his own sealing scrolls and leaving an illusion seal to make it look like the original was still there. After all, he was supposed to remove it without being seen, and that would be easier if nobody thought it was missing.
Unknown to him, Mizuki had been delayed by other factors and the lack of initial alarm had allowed those distractions to continue for longer than he'd intended. Thus his own alarm, and the discovery of the illusion seal, had gone out later. Naruto had plenty of time to figure out the Shadow Clone and had started in on some of the variant techniques tied to it. Mizuki eventually found him anyway, swore upon seeing that the Scroll of Seals was nowhere to be found, and immediately tried to kill Naruto in retaliation.
Iruka showed up, paid attention to Mizuki's rants, and then helped Naruto take down the true traitor. Naruto's use of the Shadow Clone technique to duplicate himself and his puppets had been more than enough to overwhelm Mizuki at that point, even if Iruka had dealt the final knockout blow. Naruto was given a field promotion for his participation and told to show up for team assignments later that week, after returning the Scroll of Seals. But nobody asked him to return his copies of techniques from said scroll.
It had taken Naruto six months, between missions and other things, but he'd finally perfected an idea that he'd come up with shortly after he'd become a genin. The first puppet he'd modified to take advantage of it was able to slip into and back out of the Hyuuga compound without issue, and he had celebrated. Only to end up on a C-Rank mission before he could modify his other puppets. That mission turned into an A-Rank, and he pushed himself quite hard upon returning to the village in order to not need to think about how Haku and Zabuza had died.
He successfully modified all of his puppets and built six more by the time the Chunin exams started. At the urging of his sensei, he kept his larger puppets a secret at the start of the exams on the assumption that Suna didn't think that he'd made any progress with controlling the fox puppet. Something that seemed to be correct when Kankuro had taunted him about his 'itty bitty useless puppets'.
Not triggering the release of the glue and glitter bombs sealed into a couple of the smaller puppets to hit the older boy had taken quite a bit of self-control. Though seeing Gaara smack his brother with a ball of sand for annoying Naruto had been amusing. The other demon container was apparently still far too happy about being able to sleep and saw Naruto as being part of the reason for it.
The first two exam stages had gone wonderfully after that, assuming that you ignored the traitorous sannin stepping in and giving Sasuke an evil hickey and Neji doing his best to kill Hinata. Naruto drawing Neji for the first fight of the third stage had caused him to vow to give Neji a beatdown, only to be brushed off by the older boy. But Naruto had a secret weapon that not even the Hyuuga were prepared for.
Kakashi had brushed off Naruto in favor of Sasuke, which was fine as far as Naruto was concerned. He had a plan, and needed to build more puppets and practice for it. Jiraiya showed up a couple days later, apparently having expected Naruto to seek out someone for training, and convinced Naruto to use Shadow Clones to build the new puppets while they worked on chakra control and summoning. This included Naruto signing the Toad contract, though he didn't put a lot of effort into summoning them due to not thinking he'd need them right away. At least not until Jiraiya threw him off a cliff, anyway.
The first fight of the Chunin exam tournament had started off quite boring for most of the audience, just a lot of whining and declarations that Naruto should just give up from Neji. Naruto had countered with unsealing his twenty puppets, causing Neji to scoff and point out that puppeteers can only control one puppet per finger. Naruto had countered by pointing out that he also had ten toes, connecting Chakra Strings to all twenty puppets that way. Then, instead of controlling them directly, he performed his own personal technique.
"Multi Shadow Puppet!" Naruto called, and the arena exploded in smoke. The twenty puppets were now over two hundred.
"There is no way you can control all of those," Neji said. "And even if you try, I'll just break the Chakra Strings you use to do it."
Naruto merely grinned as all of the over two hundred puppets, the twenty original and all of the duplicates, started to move. Neji activated his eyes, only to recoil in shock as he noticed that every last puppet had a chakra network of its own now, without any points on the networks to attack, and not a single one had a chakra string connected to it. They were also all very obviously moving independently of one another, forming into varied attack groups and taking advantage of local terrain in various ways. Including some of them moving up onto the walls and into the few trees in the arena.
Of course, having over two hundred puppets wasn't enough for Naruto, and he also created a few dozen Shadow Clones. Only after he knew that everyone could see that he didn't need the Shadow Clones to control the puppets, of course. Neji put up a good defense, but the initial shock had done its job and put him off of his game. Though it was actually a senbon accidentally fired straight down his blind spot from the arena walls that finished him off.
Kankuro had forfeited his match as a result of being a gibbering mess at the mere thought of the puppeteering mastery needed to perform that technique. Not that Naruto was about to tell him that the trick was a seal array in the puppets that allowed him to place what amounted to a bodiless Shadow Clone into the puppets to control them from inside, without needing a connection back to him or any mental effort on his part. Even better, they could actually scout and return information back to him.
Someday he might even figure out how those clones could see and hear without proper eyes and ears in the puppets.