Opening the door to the library the lighting seal lit up on its own.
Taking a glance around he saw an average room of about 20 square meters (sorry guys don't know how to convert this to feet or whatever is used for it if anyone knows help our friends who don't understand it) filled with bookshelves on all sides of it even to the right and lift side of the door, reaching up to the 5 meters (5.4 yds) High ceiling.
The shelves were full of books and scrolls which contains all the knowledge one would need to start on their journey as a shinobi, In the middle was a small square study table.
After taking in the scenes aizen walked around the table and went right to the shelves opposite the door, getting closer he could notice some writings on the wooden shelves themselves, " fuinjutsu." he said after observing.
Since the moment Aizen opened the door leading to this cellar he has been amazed at how versatile the sealing techniques in this world were, and at that very moment he made up his mind to learn them.
Looking through the shelves he muttered in a low voice, "learning fuinjutsu is a necessity for me, not only will it make my life in this world a lot easier but it'll also facilitate a lot of my future plans, it is basically a cheat code, the hashirama cells for poor people some might say hahaha."
Picking up a small book of about 100 pages with the title," basic fuinjutsu application and principles " Aizen couldn't help but have a frown on his face as he started having flashbacks, not of war which is what most will assume but of school and university," I hate studying." he muttered.
Walking back to the table reluctantly he took a seat and opened the first page of the book he just picked and began reading it.
At first, it described what fuinjutsu is down to the most boring details, after that it moved to when and how it's used then it went all the way to explaining the different runes and markings, their uses, their combination and much more.
By the time he came back to his senses he had already flipped through the last page of the book, "I take back what I said earlier, I love studying, it just depends on the subject and I freaking love fuinjutsu, this is so amazing that I can't get enough of reading it, I just finished and want to reread it immediately." he almost screamed excitedly.
"I only managed to comprehend about 10% of the total content and this is just the basics!!?." he exclaimed with a hint of excitement in his voice, already eager to check the other more advanced stuff but he stopped himself.
"I can't get ahead of myself I Need to completely understand this first before moving to more advanced materials, or else I'll end up with a shaky foundation and just mess up my learning process," he said calming himself down.
Looking again at the library he didn't find anything else that interested him for now, so he picked up the book and went outside closing the door behind him, immediately after he left the fuinjutsu lights turned off.
Heading to the bedroom right next to the library as he decided to just sleep downstairs he put his book on the bed then went to the bathroom and took a cold bath to relax his sore muscles after training.
Laying there in the bathtub in cold water Aizen couldn't help but let his thoughts drift.
'the state of the world currently is quite problematic, small countries are constantly battling each other for either land, resources or power, and it's us, ninjas, that they hire and send to the battlefield to die for their interest, and fight their battles, so honestly, it's not much different from my past world, minus the Petroleum of course.' he thought.
' my clan is currently hired by a small time lord to fight for the land of another country and claim it as his own to expand, the clan we're up against is the same one as mine, a medium-sized clan with no special abilities or bloodline limit, and it was during our first encounter with them about 3 days ago that I got injured and brought back here.' he remembered the screens from 3 ago which caused the old aizen to die.
Thinking to here his eyes frowned,' which reminds me, the reason the previous Aizen got injured is that he did not expect the enemy to use a fireball jutsu and was caught off guard, isn't it only exclusive to the Uchiha clan!?, how did they get their hands on it, I need to be more careful from now on, I can't rely 100% on my Canon knowledge.' he thought taking a mental note.
' anyhow I need to get used to my new body fast and improve as much as possible before my next deployment, and if can be really honest with myself, as I am now I can only rely on luck to not get killed on the battlefield, sigh.'
After spending a little more time in cold water just relaxing he dried himself up, wore new clothes, and applied new bandages before going back to his room.
Sitting in a meditative position in his bed he picked up the book about fuinjutsu, reading it a couple more times and getting a deeper understanding before putting it aside and laying down, calling it a day.
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Time skip 1 month.
In the training ground 20m(21yd) away from the wooden dummies a young kid of about 5 years old could be seen standing there, his hand almost a blur as it was constantly moving seemingly throwing something, and with each movement of his hand a *thud* sound could be heard coming from the wooden dummies signifying that he was constantly hitting the target.
Throwing his last shuriken Aizen watched it as it flew straight forward hitting the target on the dummies head right around the edges.
Watching the target Aizen saw that most of his shots with either shuriken or kunai were either on the far edge of the target or close to the middle, only one hit the target right in the middle but he knows that it was just a lucky shot.
"hitting a moving target is nothing like what I am doing right now, nonetheless I am way better than I was 1 month ago, now I at least have a certain degree of confidence to not hit my clansman," muttered Aizen satisfied with his progress.
During the past month he kept up his daily physical exercises not Skipping even a day, and not long after he got used to the body weights as he was constantly wearing them which amazed him and reminded him again that he wasn't in his previous world and of the potential of the humans in this world, so after he got used to them he increased them from 10kg(22lb) on both of his legs and torso to 13 kg(28lb), and from 5kg(11lb) on his hands to 7kg(15lb).
He also trained his sign weaving speed to an acceptable level, after all knowing a jutsu would be useless if your enemy can interrupt you in the middle of casting it a thing which was not doubled down on in the show.
From there he went on to learn 2 new jutsus he got from his library, the first one was fire style: flame thrower technique, in which he can shoot a stream of fire from his mouth at the enemy, basically a flame thrower from his mouth.
The power and range of that jutsu like many others depend on how much chakra he channels into it, in its most basic form it instantly consumes 20% of his chakra so he has to use it carefully and sparingly.
'it also mostly has to do with me being so young and not having enough chakra.' he thought as he slowly collected the shuriken and kunai from the wooden practice dummies.
But something very strange happened when he used the second jutsu he learned, the body flicker technique, he thought it was something simple and that most ninjas can use so he might as well learn it as it may become useful, although few can use it in a fight and he was right in thinking that.
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Flashback
So to test how fast he can go by using the body flicker technique he threw a Kunai from the entrance of the training ground to the forest on the opposite side and immediately weaved the one-hand sign required for the jutsu and activated the body flicker technique.
Everything was going fine till now but then when he released the jutsu that is when he noticed something wrong.
It is common knowledge that the body flicker work by using chakra to temporarily vitalise the body and move at extreme speeds that it looks as if the user has teleported.
it's also common knowledge that in that state except for a few special cases no ninja can react fast enough to avoid obstacles or even notice them in the first place before ramming into them, so it is seldom used in battle and mostly used to travel short distances already in eyesight or long ones with open terrain with and no obstacles.
But what he experienced at that moment can only be described as magical, the sound of the running river to his left was completely gone, and the Kunai he just threw seemed to be suspended in the air some distance away from him moving forward so slowly it was almost unnoticeable, running to it he could see that he controlled his body perfectly and could react just as normal as if he wasn't even using the body flicker technique, reaching the kunai he extended his hand out and caught it from mid-air before stopping the chakra flow deactivating the technique.
Immediately after everything returned to normal as if nothing happened at all, if it weren't for the Kunai resting in his hand he would have thought it was all a dream.
after getting over his shock he couldn't help but have a wide grin on his face as he realized the potential of this technique.
"If my theory is correct then the stronger I am the faster I'll be able to move in the body flicker state, as I am right now am sure some experienced shinobi could still react to me, and they'll definitely not leave a threat like me hanging around so I can't go around spamming it and only use it when am in dire straits, but with this trump card up my sleeve, my chances of survival have gone up exponentially hahaha." he thought and he couldn't help but laugh out loud.
"If I can grow just a little bit more.., even I can't imagine what I'll be able to do then, I could only attribute this to my soul, that's the only explanation." closing his eyes and taking a" look" at it, he couldn't notice any change, it was the same as it previously was.
But he was sure that it was the reason for this, his theory was that due to his soul becoming stronger he now have increased perception, far above average, and the only reason it only activated when he used the body flicker technique is that his body is too weak compared to his soul, so it can't show its true potential, only when he made his body by using the body flicker jutsu did it show its true potential.
It was basically a case of a having a small cup and an ocean of water to draw from, so he can only pick a cup size for now.
Getting over his shock he decided to test it again to know its limits, and he was surprised that it didn't consume that much chakra, but that's something he should have expected, after all, it's only a D-rank jutsu.
Another thing is that the longer time he spent and moved in that half-time stop state the more his body ached till he couldn't move a muscle.
Those were both the pros and cons of it.
"so if I train my body more I'll be able to use it for longer and also be able to draw more potential from my soul." he thought and although he figured that he couldn't do anything about it in a short time he wasn't discouraged, he could only little by little grind and unearth the potential of his body and soul.
After having his little fun and test he moved to other practices.
Flashback end
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Also during the past month, he practised tree walking and water walking exercises, as he knew how important chakra control is to a ninja.
For tree walking, he learned it in 5 days and he spent the next 15 days training water walking, which he thought wasn't so bad, after that he practised them until it was almost second nature to him, keyword almost.
And immediately after he noticed the benefit it brought him.
first of all, he didn't have to spend as much chakra as he used to on his jutsus anymore and they'll still have the same effect, including the body flicker technique.
secondly, he could now direct chakra to specific parts of his body like his legs to speed up, his fists to punch harder or his chest to increase his defence in that particular area and tank a hit.
"if I want my punch to be strong enough to punch through the ground like Tsunade and sakura do the amount of chakra control I need is..." thinking of that he couldn't help but have a shiver up his spine.
He also finished his basic fuinjutsu book and with that, he learned how to make and use storage scrolls which were extremely helpful to him, a simple alarm seal and some other stuff.
Lastly, he picked a kenjutsu book from his library and practised honing his skills with a sword or in His case small katana as much as he could.
His reasoning for this was that he will mostly be fighting in close-quarter combat, as most battles were so long and shinobi can't afford to just be spamming jutsus, so he chose something which will give him more reach and flexibility than his opponent.
As he finished collecting his kunai and shurikens he headed to the armoury, yesterday the old man, Yamamoto, have come by and informed him that tomorrow he will be deployed to the forefront and he should be ready.
Currently, he was wearing a completely black shirt, pants, ninja gloves and ninja sandals, with weights on top of them.
Reaching the armoury he opened a box on the table that he prepared before, a small grey armour rested there(basically hashirama and Madara armour but in grey colour and small to fit his size), taking his weights off he slowly put on the armour, finishing with the metallic leg and arm guards, before closing the box back. ( you didn't expect him to go to war wearing those weights did you?)
Walking to the weapons rack he picked up a chokuto with a black handle(basically Sasuke's sword) and strapped it to his back.
The kunais and shuriken and even some explosive scrolls will be provided by the clan before their departure so he didn't prepare any, they even provide swords but he took his own as it was of better quality.
Making sure everything was in place he turned around and headed upstairs, this was his first war in this world and although he was no stranger to wars he never experienced something like this, this was a completely new battlefront to him and thinking about it he couldn't help but have a smile on his face, his blood boiling in anticipation for what's to come.
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