Summary: Naruto Uzumaki, the 7th Hokage of Konoha, Jinchūriki of Kurama, hero of the elemental nations, and good friend from many, died from a mysterious illness. Never in his imagination would he have thought to open his eyes inside the body of someone who looked exactly like himself when he was around 18 years old. "Now that's unexpected."

"Speech."

'Think.'

Magic/Technique/Jutsu

Flashback/Events of the Past

Warning: English isn't my native language.

Disclaimer: I don't own any material used in this crossover fanfiction.

"Phew…" Naruto opened his eyes, looking at how the room became dark again when the blue chakra around his body vanished. It was in the middle of the night, and like usual in the last three months, he used his time effectively. He managed to fill the empty chakra network to the brim. Right now, Naruto has Jonin's chakra reserves. Not an elite Jonin, but a Jonin nonetheless. It was a good base to start with when he leaves the hospital.

He jumped into a standing position and walked to the open window. He had set up a few seals in the corner of the room, making it impossible for others to feel his energy when they weren't in the room with him. For the outside world it looked like Naruto was sleeping in his bed, even when he was standing at the window right now.

He rested both arms on the window frame and looked outside, up to the sky. He smiled while he was covered with sweat. The fresh breeze from the outside blew into his hospital room against his body. It took a lot of work, blood, and sweat, but Naruto finally managed to get this once-broken body back into a decent shape with a decent amount of chakra to start with.

No one could see his bones anymore. Since he didn't wear any shirt, everyone could see his now muscular and lean body. It was the perfect body for someone who uses speed over power. It was the perfect body for someone who favors precision, flexibility, and speed over brute strength.

Overall, his body was in perfect condition to begin the real training. He had finally finished the foundation to begin his training to relearn parts of his old skill set. He could never fight like before since he wasn't a Jinchūriki anymore. He would need to adjust his fighting style, but he didn't mind it. It was a challenge he gladly accepted.

For once, he couldn't spam his beloved Kage Bunshin (Shadow Clones) anymore like before. That meant he couldn't distract his enemy with hundreds of clones while he prepared a strong Jutsu to hit his enemy in the background. There would also be the fact that he couldn't spam Ninjutsu like he used to. Even when he leaves the hospital and begins his real training to not only learn Jutsus again but also raise his chakra reserves as much as possible, he could never obtain the amount of chakra he had before. He would need to rely on Jutsu, which weren't so chakra-taxing. He never had to worry about this topic, but now he would need to learn Jutsu that he could use that wasn't so taxing on his chakra reserves.

'I wonder if they will continue to watch from afar instead of coming to me like three months ago,' thought Naruto. He could feel the energy of one of the women who visited him three months ago in the distance. After they had given him the book three months ago, neither woman visited directly again. In fact, no one came to visit him in those three months. Not that it disturbed Naruto in any way. He focused on getting his body and chakra reserves into a decent shape. It gave him the freedom at night to train his body and refill his chakra network.

There would also be the thing that Naruto would learn swordsmanship. The book also contained the swordsmanship of the Assassin King. It was a style that relied on speed and precision. This meant that this sword style leans more toward multi-strike techniques than single-hit solid techniques.

Oh yeah… some might ask how Naruto would be able to learn swordsmanship if he didn't have a sword. He had never used swords in his life, and how should he have been able to learn swordsmanship in a world where swords were only used for decoration? It was pretty simple… Naruto discovered he had something called a Sacred Gear.

The Sacred Gear he possessed was in the form of a Jian Sword, a single-handed sword mostly used in old China. Naruto can still remember when he found himself in his subconscious one month ago and when he met his new partner.

'Huh?' thought Naruto.

He remembered that he went to sleep after he finished his training for the night. He knew this sensation… he was inside his subconscious, but it looked different from before. He wasn't standing inside a large sewer system but instead inside a temple. The temple resembled the fire temple in the land of fire back in the elemental nations to some extent.

In the middle of the temple was a podium with a sword hovering above it in the air. Naruto raised an eyebrow when he felt how energy flowed from this sword. It felt different than the energy he felt so far in this world. It was unique, as if this energy solely belonged to this sword. It was also a design he hadn't seen so far. It wasn't a broadsword or a katana. It looked like a mix of a ninjato and a broadsword. It was a one-handed sword… that's for sure.

"Naruto Uzumaki." A deep voice echoed through the temple. Naruto walked to the sword and could see blue energy surrounding it like a gentle river. The energy that surrounded the blade felt unique but also familiar to some extent.

"I am finally able to reach your consciousness." The blue energy aura around the sword pulsated while it communicated with Naruto.

"Who are you, and why are you in my subconsciousness?" asked Naruto. He crossed his arms before his chest and looked skeptical at the sword. "And what is this familiar energy that radiates from you?"

"First of all, my name is Silent Shadow. I am a so-called Sacred Gear, which is connected to the blood of the Uzumaki family. No one else besides a member of the Uzumaki family is able to form a contract with me."

"Sacred Gear? Never heard of it."

"It seems you have indeed lost your memories."

"Yeah? I couldn't even remember I was once an Assassin before I fell into this stupid coma for eight months." Naruto's face didn't change while he thought, 'Not that I could since I am not the real Naruto Uzumaki who was the former owner of this body.'

"So, would you explain why a sword exists in my subconsciousness and can talk? Never heard of talking swords."

"As you wish. I will now explain everything."

Naruto chuckled, looking back to the first interaction with his new partner. As it turned out, there were indeed other races besides humans. He now knew of the supernatural race. Everything there was to know. Devils, angels, gods, fallen angels, yōkai, and other races. Also, what exactly was a Sacred Gear?

When Naruto first heard the explanation about Sacred Gears, he was confused. How did it come that Silent Shadow was bound to the Uzumaki family? If he understood it correctly in the beginning, then a Sacred Gear would vanish when the user dies and randomly be assigned to a new partner.

As it turned out, the Uzumaki family in this world also specialized in seals. It wasn't exactly the same as in his past life in the elemental nations, but it was close enough. The Uzumaki clan made a pact with the sword Silent Shadow and bound it to the blood of the Uzumaki family.

It was also not common knowledge like in the elemental nations. Most Uzumaki also didn't know how to use seals since most of the knowledge of how the Uzumaki handled seals in the past was destroyed in an internal conflict.

Silent Shadow said it was a wonder that Naruto knew how to handle seals, even when he never learned it. Naruto lied to his Sacred Gear. It wasn't like him, and he didn't like to lie to anyone, but how should he describe his situation? He was an anomaly in this world. He wasn't supposed to be here.

He also learned that the Nine Divine Beasts of Creation were sealed by a Sage thousands of years ago. Most didn't even know of those nine beasts. Naruto wasn't sure if those nine beasts really Kurama and his siblings were. He thought that it had to be them.

After all… if Naruto Uzumaki existed in this world, then other people from his past life should also exist here, right? But so far, he hadn't found any evidence, and Silent Shadow couldn't answer this question either.

So, his first course of action would be to find evidence for his suspicion when he would leave the hospital in a few days. If he were wrong and he would free a beast who really wanted to destroy everything, then he would be the cause of an apocalypse.

Of course… he would need to be strong enough to face potential opponents on his way. Not just potential enemies he could make but also enemies the Naruto Uzumaki of this world already had. He still didn't know entirely how Naruto Uzumaki lived.

Silent Shadow was inside Naruto Uzumaki since his birth, but he couldn't see the life of Naruto Uzumaki until his death. He only knew that Naruto Uzumaki of this world didn't know how to use seals since there were no signs of sealing practice.

Seals worked a little differently in this world than in the elemental nations. The user always used a part of his life force in the creation of the seal. That meant that every single seal had a kind of marker who created this particular seal.

Silent Shadow would have noticed if the Naruto Uzumaki of this world had practiced sealing because Silent Shadow would have felt how he would have used his life force to create the seals. This was also a reason why sealing practice was so rare in this world. No one wanted to shorten their life span to create seals if there was a safe version in magic present.

Sealing magic was a weaker version of the actual sealing technique of the Uzumaki family. It was a cheap copy and not nearly as strong. There was a reason why certain beasts were still alive and not sealed yet by power-hungry individuals. They had no way to either weaken or seal them away. It would have been possible to use the sealing technique of the Uzumaki clan, but this practice was already lost.

Naruto pushed himself off the window frame and walked into the bathroom connected to his hospital room. He sighed, thinking about all the things he still had yet to learn and discover. He needed to become stronger, and he should really get an ally or two when he was out of the hospital. Someone who could support him and he could trust. So far, Naruto only had one partner, his Sacred Gear.