A Naruto Fan-Fic

'Katon: Gokakyu no Jutsu!'

"Huurrrr! Bangg! Sss..." The waterfall exploded and stopped for a moment before another wave came crashing down.

The fireball was so huge and powerful that it incinerated the water. Steam rose for a short moment before returning to normal and the hole created by the blast was concealed by the waterfall.

"Awesome! It really is 100% stronger! Cough!" The usually calm Ken exclaimed, but he was also feeling the burning sensation coming from his Lungs. It could not take the Chakra poured into it and was nearly damaged.

Bear in mind that this is just a single Gate. If he opens more, what will happen? 2 times the power? 3 times? No, it's more than that!

This is also one of the side effects of being a kid. Ken's body, especially his internal organs, they are not yet fully developed. He may have a strong physique, but his organs are still fragile.

Sure it would be solved by opening the other Gates, but growing up will also boost his strength significantly.

For example, although Ken has a huge amount of Chakra and he unlocked the Gate of Opening which allows him to double the power of his Jutsu, it could still grow larger if he grows up.

As his body grows up, his Chakra Pathway System will also grow, allowing Ken to discharge more Chakra. Just like how water in a bigger hose can contain and let out more water than the smaller one.

...

Done with the Ninjutsu test, Ken moved on to testing his physical abilities.

The effect on unlocking the Gate of Opening to the body is that it truly removes all restrictions to the muscles

'Let's try 30%.' It was really mysterious and fascinating how Ken was able to know how much strength he is going to use next.

'I should be able to keep up this output for hours before getting completely exhausted. Should be about 8-9 hours.'

'40 percent.' Strength coursed through Ken's whole body as his muscles twitched.

'Should be about 4 hours.' There was only a 10 percent difference but the hours he could keep it up were halved.

'50.' The air around Ken is slowly turning heavy as invisible pressure radiated from his body.

'Three hours at most.'

'60... 2 hours.' His hair was gently floating.

'70... 30 minutes.' Now, his hair is standing erect. As if the gravity around his head was in reverse.

'80... 10 minutes.' Veins started popping out of his neck, forehead, and limbs like they were about to explode.

'90... 5 minutes.' the veins around his pupils turned red.

'100! 3 minutes at most.' Ken felt like he is the most powerful man in the world and no one can beat him. Pain and power coursed throughout his body.

But these are just the duration he estimated for his body to not be damaged. It won't really do anything if he did not fight, but his stamina would still be unable to keep up constant activation.

In terms of speed, strength, and power, they were indeed 4 times stronger than before. His explosive speed was so fast that the n.a.k.e.d eye won't even keep up unless you have a Dojutsu.

Ken stopped and returned to normal. He now had a rough gauge on his actual strength. And as for now, the only training he could think of was to constantly activate it until his body finally adapts to it.

If before he could match Itachi in Shisui in pure Taijutsu match, then this time, with the added boost to his strength, he could probably crush them. Of course, this is just in Taijutsu.

With his many years of experience in his previous life, he already mastered the use of Shuriken and the Sword. Itachi and Shisui could not compare to that. But they are indeed talented.

Ken in his previous life was nothing like them when he was also young, taken to be trained as an assassin. Compared to them, he was nothing back then, he was just a cry baby.

Even the first time he killed someone was pathetic, he was nearly killed. But Itachi, Shisui and other young Shinobi's in this world were much, much stronger.

Ninjutsu was not really a problem for Ken. With his monstrous amount of Chakra, he could go around spamming Jutsu's. But Ken felt like he could easily learn them.

So he focused solely on strengthening his body and retraining the skills he had from his previous life. After all, his main objective was to open all the 9 Restrictive Gates.

He only learned some basic Jutsu from his Father, Itachi, and Shisui. Fire Release Techniques are the most common Jutsu's of the Uchiha Clan. So an Uchiha must learn all of it as these are seen as a rite of passage to a.d.u.l.thood for Uchiha Clan members and Ken is no exception.

Also, Glutton is able to devour Negative Energy, so Genjutsu was does nothing to him. He could stare into the eye of the Greatest Genjutsu User in the World and scoff at them like a boss. It would even give him and Glutton some Chakra. To him, Genjutsu is just a joke.

The sky is clear and the sun is scorching. Time passed as Ken tested his abilities trying to adapt to 30 percent of his body's true potential.

But that increment of 10 made Ken feel very uncomfortable. If he was not careful, he might break a cup subconsciously. That would piss his mother off.

'This is hard.' Ken thought but continued to adapt. He used chopsticks and other small objects to adapt and learn how to control his strength and muscle. But he knew that it would probably take at least a week for his body to change his normal body peak from 20 percent to 30 percent.

As time goes on and as he trains, there would come a day when his normal peak will reach 100 percent.

...

Ken went home and ate lunch and returned again to the waterfall. After training for the whole afternoon, he again went home, ate, and slept. Wake up, eat, train, go home for lunch, eat, play with Sasuke, go back to train, go home, eat, sleep.

Ken did this for 4 days straight, but he still felt exhausted at the 15th hour. His limit before was 8-9 hours and only increased 7 hours after 4 days of training.

But this made him even more determined. After all, Glutton said that he must master the Gate of Opening before he tries to open the other Gates.

This was also the 4th day since Itachi went to a mission with his team. Shisui also did not come at their usual meeting point all, it seems like he is also on a mission.

Somehow, it made Ken feel a little lonely. It was a feeling he had forgotten. His previous life as a kid in the gutter resurfaced in his mind.

He was reminded of the time he went to beg for food or a little change only to get beaten by other kids. That time, he felt hatred, anger, unwillingness, and... loneliness.

But compared to that loneliness, this time, it is different.

There were times when you feel that you want to show off, but no one is qualified for you to show off. That type of loneliness.

Ken wanted to show off his strength to someone qualified, someone "his age". And he felt that only Itachi and Shisui were the only ones that are qualified.

As he thought about that, Ken felt a little bit of anticipation in going to the academy.

'Itachi and Shisui graduated from the academy, surely, there are others like them.' With that thought, Ken finished his every 6 hours routine. But it was just improved 4 days ago.

150 Push-ups, 150 Sit-ups, and every physical training he did in his previous life. 250 Kicks on each leg, 250 punches on each arm, 1 Hour of hopping around the training ground.

The only thing Ken did not do was carrying weight. The only reason he did not do it was because his current exercise already surpassed his limit.

He planned to start it after his training would not give him much progress. Sure, it would give him an increase in his speed and strength, but Ken thought that it would better to do it in the future.

And he is still adapting with his body after unlocking the Gate of Opening. As Ken sees it, it would probably take more or less than a year before he can reach 100 percent as his normal peak.

...

The moment Ken activated his Sharingan, it immediately turned red and his vision changed. The leaves falling looked like it was slowed down by many times. The swaying of the grass looked slow and s.e.xy.

Ken could even see the details of the waterfall.

'This Dojutsu's are really fascinating. The people from my previous world would probably cause massacre just to get one of these. How terrifying.'

Ken thought. He took out a shuriken from his leg pouch and casually threw it to a leaf.

"Tak!" The leaf was cut in two before the shuriken was imbedded on the tree trunk. He could do that even without his Sharingan, but it was 100 times easier.

'Really, how terrifying.' Ken sighed in amazement. This is just the effect of having a single tomoe. If he trained and mastered it, having 3 tomoe, then it would be even more powerful. Just imagine!

....

Abilities of the Sharingan: Source is Wiki.

"Eye of Insight"

The user can see chakra, giving it colour in order to distinguish it by its composition and source. Though not as capable in this regard as the Byakugan, it can see chakra through some (but not all) obstructions and detect irregularities in a person's chakra flow, such as those caused by genjutsu influence.

The user is granted incredible clarity of perception, enabling them to read lips or mimic something like pencil movements. In combat, this allows them to see fast-moving objects and, once fully developed, offers some amount of predictive capabilities: they can anticipate an opponent's next move based on the slightest muscle tension in their body and act accordingly to dodge or intercept.

They can also read the enemy's hand seals to give them an insight of the performed technique's nature, regardless of the speed of performance, so long as the hands are not physically hidden from view. Although a Sharingan user can see these things, they also need the physical ability to actually act on the visual information.

With advanced enough prowess, via eye contact, the user can even enter the target's mind to look through their memories and even erase them within a long range for several targets.

The user is able to copy almost any jutsu they see, memorising ninjutsu, genjutsu, and taijutsu with near-perfect accuracy. They can then either perform that jutsu or modify it to suit their needs.

Again, Sharingan users need the prerequisite abilities before they can mimic a jutsu they have seen, and for that reason they cannot, for example, reproduce kekkei genkai abilities they do not have or nature transformations they haven't learned to perform.

"Eye of Hypnotism"

The user can perform what is generically called Genjutsu: Sharingan. While there are various manifestations and purposes of the ability, the better known one is to, through eye contact, suggest thoughts and actions to a target, coercing them to divulge information or act in a particular way, potentially without the target's awareness. 

In extreme cases, the Sharingan user can take complete control of the target's body, forcing them to do exactly as the controller wishes; this control is visually indicated by the Sharingan's design appearing in the target's eye. 

The Uchiha are particularly infamous for using this ability on the tailed beasts, and in fact can enter its or a jinchūriki's subconscious to more precisely control the beast's chakra. Multiple targets can be taken control of in this way, though the more divided the user's attention is, the easier it is for targets to escape this control.

This is also one of the reasons why the Uchiha clan was suspected of plotting the attack 3 years ago.

While not an ability per se, the Sharingan user can appear as if they are able to "see the future".

First, the user must perfectly mimic every move their opponent makes and possibly their thoughts and words through careful observation. Then, they suggest an action to the opponent such as hand seals for a technique that the opponent and Sharingan user already know and copy that.

With these things done, the user can complete the action even before the opponent does, possibly using the Sharingan's genjutsu to confuse or delay them.