He left. Quite some time ago, in the dead of night, he got past the guards and ran off into the night. Running to the sea and tossing himself into the water. He planned to return, and the only thing coming with him was the destruction of Konoha.
Darkness.
That was it.
Naruto waved his hand around and flipped onto his back, "Where am I…what happened?", he remembered throwing himself into the sea, but that was all.
Naruto ran his hand across the ground, grass, wet grass. Focusing every bit of energy into movement, Naruto crawled around in the dark, shivering as the water seeped through his shirt. "Eat the grass".
Naruto looked around, no movement besides his own, "Eat the grass…it'll help".
Naruto ripped the grass out of the ground and began eating. Gagging at the texture, there was no taste. Naruto let out a sharp breath as a tingling session ran through his body. The feeling in his legs slowly returned, and he stood up, falling on his butt several times before finally stabilizing himself. He got down on his knees and began consuming handfuls of grass.
A day, or what Naruto assumed to be a day, had passed, he had done nothing but eat this odd grass, shoving excess amounts of it in his pockets.
He moved very carefully in the cave. Keeping his hands on the damp stone walls as he walked. His main mission was to find food that wasn't grass. A search that ended up being fruitless.
Various days passed, or what Naruto assumed several days, he had stopped trying to count. The voice hadn't returned. He had been left alone with his thoughts, and with nothing to do, he just ate grass. He had eaten so much grass, that strange food source gained a flavor that he deemed to be a once in a lifetime experience. "The grass isn't enough anymore… It's aided you in your evolutionary progress enough" The voice said.
Naruto looked up and around, "A rabbit is sitting about a few feet away…be careful".
Naruto listened to the voice and remained low. Stepping quietly, upon laying his eyes on the bunny, Naruto burst forth and grabbed it, holding it tightly as it struggled.
Naruto looked around, large blue crystals stuck out of the ceiling and illuminated the area. Naruto looked back down at the rabbit. Naruto had seen snow bunnies, but not one like this. White fur with a black belly and two small red eyes, two large canines stuck out for about four inches and its lower body exhibited large amounts of muscle mass.
Naruto held the rabbit down and was startled at its great strength, grabbing a sizeable rock and bring it down the rabbit's head.
Repeating this for several minutes until the creature died. With assistance from the voice, he started a fire and cooked the animal.
The meat looked disgusting, thick large veins ran along its gray surface, and it continued twitching after death.
He consumed the meat without a second thought, wolfing it down at inhumane speeds, he resembled a feral animal. Any person would've found him repulsive at this moment.
Hours passed and Naruto had practically cleaned the bones, burping and sighing he added the grass as desert.
He sat up as his stomach rumbled, "What now?".
"AH, GAH!, AGHHHHH"
Naruto keeled as a bolt of pain struck. His insides melting and building themselves back up. This pain was far greater than any pain he'd ever felt. Naruto ripped up a handful of grass and ate it, the pain decreasing for a few seconds before returning full force.
His head began to pound and his body pulsed.
The grass was no longer helping.
Naruto screamed incoherently as he rolled on the floor, spewing obscenities. His body began to morph, his bones, and muscles growing and hardening, and his cobalt blue eyes turning to a cool gray. Naruto dug his hands into the ground and pleaded with whatever deity was out there to end his suffering. The answer he received was no.
On this side of the world, there is a phenomenon known as "Celeri Progressionem".
When one eats demon meat, their body reacts poorly, the mana or chakra as they would've called it back home would rip the victim from the inside out via flooding, an over-abundance of mana. Most had failed when they tried to consume this meat, and those who succeeded were driven insane. The overabundance of mana and partial demon physiology grants the user the ability to preform magic or Jutsu without the use of hand seals, and gives the eater an inhumane boost in strength.
What prevented Naruto's immediate death and insanity was the grass, subject to years of being bombarded by Mana, the grass became a vessel of condensed Mana. Also known as ambrosia. Activating the moment, Naruto's body began breaking down after the consumption of the demon meat. With each cycle of repair, Naruto began a process of enhanced development. His twelve-year-old body pushed to become something much stronger.
Naruto let out screams that resembled that of a dying animal for several minutes before stopping.
Taking deep breaths and looking up. Moving his now thick, spiky hair out of the way. His body twitching and pulsing wildly. Naruto couldn't have been more surprised by this strange turn of events.
He flipped onto his back and took a few deep breaths. His hunger had faded completely and despite the mental exhaustion, Naruto never felt more peace. "It's time to find a way out, get up" The voice called out. Naruto stood up and looked around, the meat had awoken a hunger that needed to be satisfied.
Consuming any mana infused animal he found.
Let's turn the clock back a few days. Hiruzen sat in his office, practically ripping his hair out, his long time friend Danzo watched him carefully, "I think it's best to survey the surrounding nations. I might've just been a stupid stunt to scare us."
Hiruzen looked up and grit his teeth,
"And do you plan to provide the man power for that?"
"Of course, Hiruzen… I'm the reason we're in this mess in the first place, had gone and retrieved the boy myself, then this situation wouldn't be happening." Danzo said, as he stood up, began walking out. "Word has not reached the daimyo yet, so at least there's that." he said as he walked out.
Hiruzen grabbed his pipe, in the last forty-eight hours, Konoha had lost its most powerful asset and the son of a former kage and clan heiress.
A tall man with long, spiky white hair landed on Hiruzen's window sill, "Any luck?"
"No and you?"
"No, and I've had every spy in fire country looking for him, we plan to start looking into the massive caves near the border early tomorrow morning" The man said.
Hiruzen rubbed his temple and sighed, something he had done a lot, "And what about the daimyo?" He asked. "He's completely unaware, for now."
The man looked to the side and sighed, "What do you want, Kakashi?."
"I want to help".