Disclaimer: I do not own Naruto. Without further ado, and with no more formalities, let the show begin.
It was only a matter of time. No cage was perfect, and not even Gods were truly omnipotent. It took years, but finally the Kyuubi broke free. It was inevitable, really. What cage could possibly hope to hold back such a monster forever? For all his genius and talent, Minato was no Mito Uzumaki. And for all the Death God's power, it was not infallible. It took 18 years, but finally, Kyuubi was free.
It happened on a warm summer day, this calamity. One Naruto Uzumaki was on a date with one Sakura Haruno, trying (rather successfully, for once) to woo the pinkette. He had no idea, no forewarning at all. He was interrupted mid-sentence by a terrible, agonizing pain. It felt as if he was being inflated from the inside, his being forcefully stretched to its limits. He had not even a moment to truly understand what was happening, as skin tore, bones cracked, and his organs were squished and forcefully ejected from his body. He was dead, in a terrible and painful instant. Blood sprayed, covering his horrified date, which could only look on, uncomprehending. With a roar that shook worlds, the Kyuubi burst free with the spray of its containers life blood.
The monster rapidly expanded to its true size, towering over the tallest of mountains. The demon was so large, the very light of day was lost, and a shadow was cast over the land. For a moment, all was silent. And then the screams began; screams of primal fear as the people of Konoha once again gazed upon a being which held no peer. In the entire world, there had never been another quite like the Kyuubi, not even its forefather, the Juubi. Nothing else possessed the sheer malice of the demonic fox.
For a brief instant, Kyuubi gazed down at Naruto's remains with what might have been regret. They were comrades, perhaps even friends, but the Kyuubi cared first and foremost about itself. Truly, what was the life of one human, no matter how great, to a being who would live forever. Kyuubi would not be chained to Naruto, dragged down into Hell upon its containers death, no matter their bond.
And then darkness took over its crimson gaze, like freshly spilled blood; the malice and hate which intricately constituted the Kyuubi's inner most essence, brought to the forefront. Jutsu, varied in both strength and element crashed against the mighty being, but all for naught. Still, Kyuubi would not allow the Shinobi to marshal their forces this time. It had made that mistake once, and it would only happen once. This time, there would be no mercy.
A terrifying pressure bore down on Konoha as the mighty demon gathered its energies, the massive and dark power gathering into a ball in front of it. The ball condensed down to the size of a mere toy, but a crushing pressure was exerted upon the world. And then the Kyuubi ate it. The Bijudama tore into the residential district, exploding with 5 times the force of the weapons of the Old World. Nothing remained of Konoha but ash in the wind, a steadily expanding and rapidly moving wave of fire spreading out from the ruined village. It would consume all of Fire Country, and its 3 closest neighbors.
Kyuubi gazed around at the destruction it had wrought. Truly, it had not used so much of its power in centuries. Satisfaction filled the monster; never again would this village enslave it as a weapon of mass destruction. It was not some tool for mere humans to use in settling their petty disputes. It was time the world was reminded of that fact.
Authors Notes: This one has been circulating my mind for years now. Truly, this isn't my best work, but it doesn't need to be. It will not be continued. At best, this would be a tale of the destruction of humanity.
I always found it slightly ridiculous that someone like Minato, an admittedly talented man, could possibly seal away such a monster forever. He had the talent, and he had the genius, but he had no experience. Fighting your fellow man is one thing, but nothing can truly prepare someone to face a being like the Kyuubi. I won't even get into how impossible most of the crap that happened in Canon was, considering how powerful the Kyuubi was made out to be. Anyway, leave me a review, if it pleases you.