Seven years later

A Raikage's training doesn't stop until they reach their full potential; this has been true for all Raikages until now, and it was true for Sato as well.

*Bang*

Two fists rammed into each other, one small and one large. Sparks of electricity were crackling around these two fists.

"Hahaha! What happened, Sato? You can give up if you feel tired."

The owner of the large fist, the Third Raikage, was smiling ferociously. His face no longer had cracks on it; the aura of decay had disappeared from his body.

He clearly was no longer an edo tensei but a flesh-and-blood human.

*Bzzt*

The two fists were trying to overpower each other; lightning crackled harshly from the smaller fist, as if proving itself against the larger one.

"Shut up, old man; today I will beat you one way or the other."

A slightly young voice spoke from the other side; this voice came from a thirteen-year-old boy, a boy who had lightning chakra crackling around him.

This boy was Sato; a full seven years had passed since the day he began his Raikage training.

Today was the day he had graduated from the Ninja Academy, and today was the day he had decided to officially finish his Raikage training.

"Try to survive this old man."

Sato smiled and jumped back, his muscular legs pushing against the ground. With one jump, he disappeared into thin air. His speed was fast; he was almost catching up with the third Raikage.

*Crackle*

Sato appeared a few meters away from Third Raikage and made a ram hand sign. Suddenly, the blue electricity cracking around him changed.

"Lightning release: black panther."

The electric current transformed from blue to black, and the wild black sparks around Sato's body gathered together and formed a ferocious black panther.

*Growl*

This black panther growled like a living being and ran towards the third Raikage.

"Good, but you can do more. I have trained you for seven years; I know this isn't your limit!"

The third Raikage didn't dodge the black panther; he bent down and glared at the cat.

*Boom*

He fiercely chopped the panther's neck when the beast ran close.

*BZZZT*

The black panther howled and collapsed into a bunch of black lightning arcs, which scattered around the third Raikage.

"Hmm?"

Suddenly the Third Raikage's instincts gave him a warning, which startled him. His defense was absolute; he rarely ever felt he was in danger.

*Bzzt*

But the Raikage trusted his instincts and vanished, and just after he vanished, Sato's grim voice came from the sky.

"Lightning release: Railgun."

*WHOOOSH*

A beam of what looked to be pure energy was ejected out of Sato's hands. The third Raikage's eyes almost popped; his incredibly fast nervous response let him see what Sato did.

What Sato fired wasn't a beam of energy.

*BOOOOM*

It was a Kunai. A Kunai accelerated with so much speed that it lit the surrounding air on fire.

'He calls this forbidden jutsu the Railgun? Lightning chakra cloaks can do something like this?!'

Third Raikage backed away again and again; the ground was shaking, and a mushroom cloud had formed where the kunai had crash-landed.

The Third Raikage looked at the destroyed land and sweated a little. This railgun had the potential to seriously hurt him.

"This jutsu, how does this work, Sato? You have created an S-class jutsu! This kunai has power comparable to a tailed beast ball."

The third Raikage was excited; not only was this jutsu incredibly powerful, it also had the potential to injure him greatly.

Until now, the only thing in existence that could hurt the third Raikage was the third Raikage himself.

But now he had to add Sato's new forbidden jutsu, the Railgun, to the list. The lightning-style chakra around that kunai had the power to penetrate his chakra cloak. He could tell.

"Tch, you dodged it; I was preparing this as my surprise attack."

Sato clicked his tongue and landed on the ground. His lightning chakra cloak vanished as soon as he touched the ground.

"Do I pass, old man?"

*Bzzt*

The third Raikage appeared before Sato and cancelled his lightning cloak as well.

"Of course you pass. But that last jutsu, how does it work, and how many times can you use it?"

Raikage was impatient; he wanted to know how Sato created such a strong jutsu.

Sato smiled and rubbed his wrists. The Railgun had a really strong kickback. Even with the lightning-style chakra cloak, his wrist hurt.

"That jutsu? It's something I created after I noticed that fluctuating magnetic fields can move metal objects."

"I named it the Railgun; I accelerate a Kunai using lightning release chakra mode's electromagnetic field."

Sato explained Railgun in the most basic terms. The railgun was a weapon invented in his previous world. Sato had used its concept to create his own version of the attack.

"So it uses the electromagnetic field that makes our body tougher? I see. I think I understand how you did."

"This is an amazing invention. Sato, we can create artificial weapons using this jutsu. It would be much cheaper than our chakra canon too."

The third Raikage was lost in thought; he was a lightning-style researcher himself; he was the man who invented black lightning after all. He understood how precious Railgun was.

But soon Raikage shook his head; he would think about this later. He had to congratulate his student on his graduation. Patting Sato's shoulder, Raikage smiled.

"Congratulations, with this, your training has officially come to an end."

"You have reached your limit, both in chakra and strength; you are as strong as you can be."

"With the black lightning and railgun mastered, you can be considered slightly better than my son, the fourth Raikage."

"It's a shame your natural chakra can no longer increase. It's a good thing that you are still young; you will eventually reach Kage-level chakra reserves when you grow up."

Raikage patted Sato's head.

"I hope Railgun doesn't need too much chakra; your body has reached a limit, right? You cannot go higher than Jonin reserves at your age. You know that, don't you?"

Seven years was a long time.

For seven whole years, Matatabi had been feeding her chakra to Sato. But after Sato reached Jonin-level reserves a year ago, his chakra amount stopped increasing.

No matter what he did, his cellular limit had been reached; this was his genetic limit as a pure human. In fact, the only reason he could even reach this level at his age, was because a tailed beast helped him all day long.

He would need to train for decades to reach such a level on his own.

"I know, old man; I am a thirteen-year-old Jonin. As an adult I will have three times as many cells as I have now."

"That's three jonin worth of chakra in one body; I know I will have kage-level chakra reserves by the time I am in my mid- to late-twenties."

Sato waved his hand. This might be a great thing worth celebrating for a guy as average in talent as Sato was. But Sato wasn't satisfied with this.

He will have to fight the fourth great ninja war against Madara and Kaguya when he is 17. He does not have enough time to reach Kage level naturally.

"Whatever, I will think about it later. Old man, I have finished my training. I hope you won't stop me from doing what I want to do anymore."

"Hinata's feeling sad since her mother passed away and gave her Byakugan to us for experiments. I know her mother wanted this, but Hinata still feels bad."

"I want to take her out of the village and get some fresh air."

Sato said seriously, as if he wanted to do this just for Hinata, but the fact is, he wanted to leave the village himself as well.

Seven years had passed, Naruto's generation was about to graduate soon, and Sato had a lot he wanted to do before the world officially falls into chaos.

His strength had also reached a genetic limit; sure, with the chakra cloak, he was a kage-level Ninja now, but he still wanted to increase chakra reserves.

After all, better chakra reserves mean more power. But he didn't know how to increase his chakra; the hidden cloud didn't have an answer yet. So he decided to go out into the world to find an answer on his own.

The world was filled with mysteries; there had to be a solution somewhere, a way he could overcome this genetic limit.

A/N

I have a new novel, One Piece : Firefist Ace, you can find it from my author's page

Advanced chapters ahead on patréon

www.patréon.com/ImagineMaker