Kingdom Hearts, Naruto Key to All Hearts

**A/N This is my first story uploaded so go easy on me I'm new.**

**(Disclaimer: I do not, now will I ever, own Naruto or Kingdom Hearts)**

**Key to All Hearts**

A sigh resonated throughout the forest as one Naruto Namikaze finished unlocking his chakra at the tender age of five. Looking around, he was slightly curious with just how dark his chakra was since it was pitch black in color and he was sure everyone else had light blue chakra. The only other person he read of that had black chakra was that of Madara Uchiha. Suddenly, a thought came to him. _I wonder how he and Hashirama got so strong, so fast_. Because in every text book they had it never showed a progressive arc of their power only that they suddenly appeared as godlike figures in that time of shinobi while now they were legends and myths to all but the highly informed and if Naruto was one thing, it was well informed. He didn't really brag a lot because it tended to get people killed but he had a better spy network than Jiraiya because the world around him was his spy.

Naruto hummed as he walked to a tree and felt the bark of it; sinking his chakra deep into the wood, he watched as in his mind, years flashed by with countless battles fought either on this tree or around it all the way back to when Hashirama created this tree fighting Madara. Looking to his left, he stared at the statue of the man he was to surpass. In his mind, he recognized that Madara was really much stronger than he let on, even to Hashirama. He could tell easily because Madara was rumored to have unlocked the final stage of a bloodline that was derived from the Sage's own bloodline. While deluded, the bloodline was still ridiculously powerful and he also knew a solid fact that showed that Madara was a lot more cunning than he let on: he never smiled.

When rivals fight, they always have identical smiles of satisfaction on their faces no matter how small. Madara never smiled when he fought Hashirama it was always a calculative glare. He gave Hashirama a look that people would give to an experiment. Hashirama was, and always will be, the ultimate experiment for Madara. He was in all honesty only testing the scope of his power against Hashirama's power and it was no match. The Rikudo Sennin's power was really derived from his eyes and his body evolved to fit that power. The Senju do not have the eyes so their body has no reason to evolve further but the sharingan is based solely on evolution and unlocking greater potential so he knew that when Madara learned this, he cut off the experiment by staging his death in the same valley Naruto was currently standing in: The Valley Of The End.

Leaping off the cliff, he felt the rush beside him as the waterfall continued to roar in his ears before he fell into the water and kept swimming below until he saw light and surfaced in the interior of a cave. As he looked around, he could still feel the residual oppressive chakra that still lingered in the place and he went in search of the source. Walking around a corner, he suddenly caught the full brunt of the malice and hatred all contained inside of this dark chakra so without even a flinch, he looked up at the shriveled old body of the man he had vowed to surpass. Leaning back in his throne, Madara Uchiha lay still and dead to the world around him as his age finally did him in and Naruto had the privilege of looking at the dead husk that left behind one of the greatest scientific minds that will probably ever grace this mudball of a planet. As he stepped closer to the corpse of the greatest Uchiha in history, he could feel the chakra that still had not left the man and he looked down as his chakra wove a seal that he had trained an entire month in fuinjutsu in order to create. A week to learn chakra weaving and a week to learn the mechanics of sealing while two weeks in between were dedicated to tweaking the explosive seal to see if he could recreate one of the Seven Swords of the Mist before deciding he would just steal it when he got stronger.

Holding his hand out, Naruto watched as the chakra in the air was all absorbed into his body and he could slowly feel his reserves build up causing his chakra pathways to widen or else explode from the pressure forming from the massive amount of the stuff he was getting. Finally touching the corpse in front of him, he added more chakra to the seal as on muscle memory alone, the corpse almost beheaded him in one quick slice from the kusarigama that was whistling towards his head. Clenching his hand into a fist, he felt as his muscle mass became denser and his regeneration combined with both Hashirama's and Madara's. Apparently, Madara took some of the cells off of Hashirama in an attempt to gain the Rikudo Sennin's dojutsu, the rinnegan. Going through the memories of the legendary ninja, he made a note to study up on jikukan jutsu as it was an extremely powerful class of jutsu that apparently Minato had only scratched the surface on.

Focusing on the air in front of him, his eyes swirled into the sharingan before the tomoe hollowed out and bars connected them to his pupil and a rip appeared in the air and he was sucked into it before it slammed shut after him. Appearing in an expanse of white, Naruto looked around before he activated his sharingan and examined the strange place. "I wonder how I ended up here. Although, in all fairness, it was my first time travelling through time and space so this must be an unfortunate mistake." He mused before beginning to use the technique once again before a disembodied voice resonated throughout the dimension.

**"You have walked very far down the path of darkness, child. You've gone down this dark road much farther than most and it's even more impressive that one so young can do so much. You may just be a pivotal force in all of the realms and as such you need a weapon that fits one of your most distinct traits."** It said before in a flash of darkness, a blade appeared before him that looked almost like a key if you didn't take into account the hollowed out heart in the teeth area that looked like it was made to not only be used as a hook but to create very gruesome and traumatizing kills… He had never seen something so beautiful in his life.

Grasping the handle of the weapon, he blinked as a name appeared in his mind and he connected with the weapon so he could get a general outline of the power of the blade only to blink again in surprise. "The Keyblade of People's Hearts, huh; so this has the ability to absorb other's hearts and can unlock any lock including the lock to the world's 'heart'." He said as he gazed at the blade before a rare grin spread across his face as the world around him was covered in darkness and he was returned to his own realm.

Appearing back inside the cave, he held his hand up to the sky sending a tower of darkness up and into the clouds while he sent out a pulse of darkness around him like a sonar wave to locate this world's keyhole. Snapping his head towards Konoha, he hopped out of the hole he made in the roof and took off in that direction since not only did he get a blast back from the keyhole, but another artifact that was hidden in an underground bunker in the Hokage Monument.

(Konoha)

Blasting through the gates, Naruto stayed focused on the Monument as he was propelled forward by jets of flame from his feet, a method of flight created by Madara after handing Oonoki his ass on a silver platter along while beating the stuffing out of Mu. When he reached a close enough distance to Hashirama's face, he reared a chakra-packed fist back before punching the cliff face and even he was surprised when he made the entire head along with the Nidaime's and Sandaime's crumble into dust. Landing in the now open area, he stared at the two capsules containing the only two from the Uzumaki clan that ever lived in Konoha: Mito and Kushina Uzumaki. Frowning, he put a hand on both capsules as darkness pooled under them and sucked them down into his section of the Negative World which was massive even without the Darkness Keyblade but with it he owned almost a fourth of the place. "Naruto!" he heard the old voice of the Sandaime behind him and he could sense about 20 ANBU behind him as well as the unmistakable chakra of both Kakashi and Itachi.

"I am flattered that you would bring so much backup to deal with a child as well as bringing both Kakashi and Itachi as well. I honestly did not expect you to take me more seriously than you did Danzo." He said as he turned partially with his sharingan glowing in the shadow of the opening in the cliff wall. "However, do not think this will save you. While you have backup, I have absorbed the body and chakra of a man who was fighting in the clan wars ever since he could walk and although I am not large enough to effectively use his physical prowess, I still have a genius mind that is picking apart his fighting style at this very moment and fitting it to my current size." He said as he crossed his arms and they started to feel his chakra rise as a dark aura covered him and his keyblade appeared beside him before starting to orbit his body.

Smirking, he watched as some of the ANBU were forced to their knees by the oppressive feeling of his chakra alone and he wasn't even letting it outside of layering his body. "Kneel" he commanded as his chakra expelled from his body to encompass the entirety of Konoha in a dome of darkness and every citizen of the great village was forced to their knees in submission. Walking towards Hiruzen, his keyblade stopped floating beside him before entering the Sandaime's body and drawing out an ashen white form of Sarutobi that was quickly absorbed by Naruto and he did the same with Kakashi and Itachi. "The rest of you ANBU are not worth wasting the time it would take to absorb you. You can all watch as I absorb the core of this world," he told them as he waved his hand and a door of darkness appeared beside him and he stepped inside.

Landing in Kumo, Naruto looked around at the people looking at him in shock for a moment before most of the people on the street came at him at relatively fast speeds only for all of them to be decapitated in a quick swing before he absorbed them as well. Naruto crouched low enough to put his hands on the ground and everyone watched in awe as he melted away the ground in front of him and as the road disintegrated, he saw the large keyhole appear before him in a flash of light.

Stabbing his keyblade in there, he slowly pulled out a large, glowing heart-shaped object that he touched and absorbed before his body exploded with power as darkness and malice were expelled from his body and covered the world in darkness as the sky turned black and his eyes were the only thing shining through the darkness as scarlet slowly turned a blinding white and concentric circles appeared in his eyes with tomoe swirling on each ring in a hypnotizing manner before he absorbed all of the darkness back into him and started to chuckle before it turned into full blown laughter as he smashed a fist against the ground and watched in satisfaction as the world split in half from his strength. Knowing that his body with the amount of his power would need several women to keep him satisfied when he reaches puberty, he sent out several darkness clones as he started to swirl as he was sucked into a vortex and disappeared.

**(A/N All flames will be used to grill my world class steaks! Nom nom nom!**


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