Disclaimer: A guy named Kishimoto owns it all. There are probably several corporations with big, intimidating legal firms on retainer involved, too.
Summary: Lots of people have postulated that Naruto's good at financial planning. Let's follow that thought a little farther into the future.
AN: I think the ending of this is pretty weak. Also, I had a devil of a time figuring out how to spell "peripherally."
Accounting no Jutsu
A little-known fact is that Uzumaki Naruto has been balancing a budget longer than he's been molding chakra. It began when he started writing down how much spending money the Third gave him each week, and then began subtracting from it with every purchase he made.
This had a very interesting side-effect when he was nominated to be the next Hokage.
When Tsunande announced he was her successor, the council protested his worthiness. Since they couldn't just say "He's the Fox" or risk getting beaten up by the Godaime (Hyuuga Hiashi in particular wanted to avoid that fate), they decided to be sneakier.
It was that same Hyuuga Hiashi that noted that Naruto was an impatient, inarticulate imbecile that wasn't very aware of just what the heck was going on around him. He himself was very very aware of this, and he frequently thanked his ancestors for it, since it meant that the Fox didn't know that the eldest daughter of the Hyuuga main family was desperately in love with him.
So, knowing that the Godaime hated doing the paperwork, he cleverly proposed that Uzumaki be assigned some bureaucratic responsibilities to prove to the council that he wasn't just a "loud idiot."
The fifth saw an opportunity to dump her most hated responsibility off onto her most annoying (albeit least politically dangerous) detractor. She jumped at the chance.
Only the Third had actually known that Naruto had been quite successfully managing his own money since the age of four. Jiraiya had been peripherally aware of it, since he had pilfered Naruto's frog purse so much, but he had always been more concerned with the way Naruto criticized his own book-keeping. The nagging got so bad over their training trip that, enraged, Jiraiya had flung his bank-book at Naruto's head, shouting that if his idiot apprentice could do a better job, then he should damn well put his money where his mouth was.
It wasn't until a month later that Jiraiya realized that Naruto was putting Jiraiya's money where Naruto's mouth was, but by then he'd gotten his first bank statement and realized that Naruto knew what he was doing.
(Incidentally, Naruto also skimmed off the top. He stole back every last yen Jiraiya had ever stolen from him—sevenfold. The Frog Sage still hasn't caught on).
Anyway, it came about that Naruto was put in charge of the finance for the reconstruction of an apartment building that had been ravaged by (ironically enough) an Akatsukai attack. The council thought it would be a good way to undermine the boy's popularity and his status as 'next Hokage.'
So when the project was finished three weeks early and massively under budget—the first under-budget project in Konoha history—heads turned. Turns out Naruto had gotten angry over the blatant disrespect he was getting and bet the site foreman he could do as much work as their whole labor force.
Laughing, the foreman bet "double or nothing" that Naruto couldn't.
Naruto spent a day learning everything he could about construction. Day two, he used Taijuu Kage Bunshin. Ditto Days Three through Eight, when the project finished. Naruto, in a bout of generosity, ended up paying all the other construction workers under the table, while the company got nothing. It was, broadly speaking, a publicity coup.
Tsunande, sensing a chance to offload yet more of her hated paperwork, began giving Naruto more and more responsibilities, much to the council's growing horror.
It's interesting to note that every Hokage had their own side-projects.
The Third, who had been a jounin instructor before becoming Hokage, had redesigned the Academy curriculum towards the current focus on teamwork.
Naruto restructured the academy bookkeeping. He squeezed an additional 15 out of the budget, allowing the Hokage to finally authorize that pay raise for the academy instructors and build the new facility.
The Fourth, an amateur seamster, had redesigned the ANBU's uniform.
Naruto reworked the ANBU payment scheme into an incentive/commission-based system. The average ANBU witnessed a net 20 salary increase. Mysteriously, members of ROOT, the semi-illegal extremist wing of ANBU, found that under the new system they had a hard time making ends meet, and thus were too busy working to bother the Hokage much.
The Fifth, a legendary medic-nin, had increased the hospital's effectiveness threefold.
Naruto implemented the concept of "medical insurance." The average civilian witnessed a co-payment drop of 20. The average shinobi witnessed a co-payment drop of 40. The hospital, now that they had a steady income instead of a sudden unmanageable influx following a major battle, witnessed an effective budget increase of a staggering 80, by the time Naruto was done reworking supply contracts and utility bills.
What really got Hiashi's goat, though, was when he realized that his own Hyuuga House was witnessing the same sort of radical new efficiencies. He tracked it to his own daughter, Hinata, who was suddenly the overwhelmingly popular choice for Heir with the Elders ("Not like the Head fights much anyways," one particularly venerable grandfather had remarked. "Better a Head that's good with money").
That wasn't the infuriating part. The infuriating part was when Neji passingly remarked that Naruto had been coaching Hinata's accounting. The sudden financial windfall was just a side-effect of his oldest daughter trying to get the Fox to date her!
Finally, it was a wildly popular Uzumaki Naruto that was nominated as the Sixth Hokage. By that time, the council didn't dare speak against it, or risk getting removed from office themselves and replaced by someone more interested in saving their constituents' money.
In his first meeting with the feudal lords, the Rokudaime announced that the Hidden Leaf village would beat the price of any village for any C-class or higher mission by 10. And they did.
Within the month, the Hidden Cloud, Stone, Mist, Waterfall, Rain, Grass and Snow villages approached Hidden Leaf to create or renegotiate treaties. By the time those meetings were finished, non-aggression pacts had been sighed with financial repercussions so severe a village was risking insolvency by invading Hidden Leaf. Most Kage didn't know about that last part until they talked with their accountants once they got back home, though.
The funniest part, though, was when Hidden Sound went bankrupt and its assets had to be sold off to lenders.