Itami Sarutobi is a shinobi who was born into the Sarutobi Clan, during the Warring States Period. He also has a powerful demon called Hidou sealed inside him.
Itami stands fairly short, but is incredibly muscular for his height. Despite his old age, Hidou has kept Itami in his prime. Itami's body is still in peak condition, and although he has lost no hair, it has turned white as snow with age. His hair is fairly short, and is spiky. He also sports a goatee, because those are cool probably. Itami's eyes a blue-ish green, and could be described as teal or turquoise. Itami often looks serious outside of fights, but can most often be seen with a smirk across his face while in battle.
Itami often wears a long black cloak, with a thick white stripe across his chest with decorations of some sort, don't ask me. Under his cloak, he seemingly wears a sort of plate armor, more akin to a knight's than a shinobi. This armor comes from the time of the warring states period, and Itami wore it because he wanted to look cooler than other people with their silly Samurai armor, like who do they think they are wearing that?
Itami, being born in a time of constant war, was forced to grow up quickly. Despite this, he always tried to keep things as light as possible, and would often joke around with his comrades, or even taunt his enemies. But as the wars raged on, he felt himself becoming more and more emotionless, and he hated it. He became accustomed to war, and soon he stopped feeling remorse when he killed, it became a normal part of his life. Throughout his life he tried his best to bring peace, but failed time and time again. This drove him to do some very questionable things, which he greatly regretted later in his life.
Upon the time of his unsealing, Itami was afraid that he would damage the current world, so he kept to himself for decades. But upon finally seeing this new world, Itami was overjoyed to find it in peace. He then decided that he would do anything to keep this peace, to try and pay for his previous actions.
Itami was born into the Sarutobi Clan during the Warring States Period. He was born about ten years before the legendary pair, Hashirama Senju and Madara Uchiha. He had many siblings, but as was common place in the time period, most of them died young. Itami learned early that only the strong could survive in this cruel world, so he had to become strong, not only for his own sake, but for everyone's. He was trained from the moment he could walk, learning the harsh way of the shinobi as a young child. Itami's natural talent was nothing special, but he had a knack for learning new skills extremely quickly. To become stronger, no, to survive, Itami trained constantly when he wasn't in battle. By the time he was 20, Itami was able to use all 5 of the basic chakra natures, like his more modern day clansmen, Hiruzen Sarutobi. Itami was able to learn them much quicker than Hiruzen though, as Hiruzen was simply training to become stronger, Itami was training to survive. Itami mastered not only ninjutsu, but every basic component of Shinobi combat.
Later on, Itami began to notice how little he cared when he killed someone, not only that, but how he no longer even flinched when a comrade was killed in front of him. Itami despised this, beginning to not only hate himself, but this dreadful world which was turning him into what he thought was a monster. Itami decided that he could no longer live a life surrounded by death, that this life wasn't one worth living. Itami fled his clan, running off on his own. He hoped to live out the rest of his life in solitude. After travelling for some time, Itami came across a very special forest. In this forest, lived a village of apes, lead by who they called the Great Ape Sage. Itami lived with these Apes for several years, learning their ways and eventually being taught the ways of Sage Mode from their leader.
What he learned there inspired him. He learned that the world wasn't all terrible, and instead of fleeing from it, he should try to change it. So, he tried. Itami traveled back to the world of Shinobi, hoping to find a way for peace. But, no one believed that it would be possible. Most thought he was crazy for believing that there could ever be peace. All these people knew was war, they could imagine nothing else. The battles continued, not even slowed by Itami's efforts. Itami quickly grew frustrated, and it was then when Itami decided that talking would get him no where. Peace could only be achieved through war, he needed to use his new found power to unite the world. He found that he could win most battles easily, but he was making little progress, there was simply too much fighting. He realized that he would need even greater power if he ever wished of bringing peace to the war torn world.
Itami traveled to a shrine, where a demon named Hidou was sealed. He figured Tailed Beasts are too mainstream, y'know. Itami easily defeated the guards of the shrine, allowing him easy access. Using his Fuinjutsu skills, Itami sealed the powerful demon into himself, in the same way you would a Tailed Beast. But, Itami wasn't expecting the Demon to be quite as powerful as he was. Hidou, ecstatic about not only being freed from the shrine, but also being sealed into such a powerful body, overpowered Itami's mind and took control. After years and years of being sealed, Hidou had developed a massive thirst for destruction. Using Itami's body, the demon went on a rampage. Itami, though he had no control, was still able to watch in horror as his body was used as a puppet.
Eventually, the rampage lead Itami into battle against the Senju, and Uzumaki clans. In his normal form, Itami could have been considered a match for Hashirama Senju himself, as the Senju had yet to reach his peak. With Hidou in control, Itami outclassed him completely. Even so, Hashirama wasn't the only one there. Hidou was eventually defeated by sheer numbers, along with the power of the Senju bros. It was deemed too dangerous to try to remove the demon from Itami, so the Uzumaki clan simply sealed Itami as well.
The seal finally broke several decades later, at the time of the Fourth Shinobi World War. Itami hadn't been prepared for Hidou's power before, but now he was, and was able to force back control of his body immediately after being unsealed. Itami was still frightened of Hidou potentially taking back control, so he stayed as far from civilization as possible for many years, training his power so he could better control the demon. Eventually, Itami was able to at least partially control the demon, and use it's power for himself. He then traveled back to the civilized world, and found it in times of great peace. Itami was extremely happy, seeing as even though he failed to bring peace, someone must have finally succeeded. Itami did not cease his training however, and kept growing stronger and obtaining new techniques that hadn't even existed yet in the time he'd been born. He traveled around the world, observing techniques and fighting styles from many different places, then copying them for himself to become stronger. He also began taking jobs as a mercenary, for extra practice against real opponents.
Itami Sarutobi is an immensely powerful shinobi. Some people may describe him as a Jack of all trades, master of none, but those people would be mistaken. A better description would be Master of all trades, jack of none.
Chakra Reserves, Potency, and Control
Though Itami originally had incredibly average reserves, his massive amount of training has expanded them to monstrous levels. Hidou has also greatly expanded Itami's reserves, though less than a Tailed Beast would. Hidou could be said to have nearly as much chakra as the One Tails, which is still quite impressive, seeing as Hidou's chakra reserves aren't his main power. His chakra control can be described as far better than even master medical ninja, making his reserves even more impressive. Additionally, his chakra is incredibly powerful, partially due to Hidou and partially due to his own strength. When Tobirama Senju used the Chakra Exertion Technique, it was enough to put cracks in the cave he was in. If Itami was in the same situation, the entire cave would have collapsed. This all combined makes it so Itami can easily use large amounts of powerful jutsu without very much trouble at all.
Life-Force and Stamina
Hidou has granted Itami and incredible life force, more powerful even than most Uzumaki. Hidou naturally channels his chakra through Itami's body, constantly healing it from any damage it may or may not take. He even enhanced Itami's immune system, flushing any diseases or poisons from Itami's body. Additionally, Hidou all but gets rid of the fatigue toxins in Tentei's body, granting him massive reserves of stamina. Even though Itami should physically be in his sixties, Hidou has greatly reduced the toll aging would take on his body, making Itami look not a day older than the day he sealed Hidou into himself, which he did at the age of 35, in his prime. Hidou does this in an effort to keep his host's body alive, as Hidou is unable to exist in physical form without being sealed into a body, also, like a Tailed Beast, Hidou would die if Itami died.
Itami has mastered all five of the basic chakra natures, Fire, Wind, Earth, Water, and Lightning. He obtained these through extreme amounts of training, and due to his ability to learn new techniques and abilities at astounding speeds. His affinity lies in Fire Release, which he can use to great effect. His fire release jutsu are hot enough to melt through solid steel, and powerful enough to incinerate forests in mere instants. He can also use the flames to enhance his taijutsu or his bukijutsu, by coating his body or weapons in flame (which he himself would be unaffected by). His skill in the other elements are to a lesser extent, but he is still considered a master in them all, able to use extremely high ranked techniques of all of them.
Itami is highly versed in the Shadow Clone technique. He is able to create over a hundred shadow clones with little effort, due to his immense chakra control and potency. He can also use shadow clones to create thousands of shuriken or kunai to completely overwhelm opponents.
Medical Ninjutsu is one of the few things Itami can't be considered a master in, but he is still quite well versed. Even while using nothing more than basic medical ninjutsu, Itami's chakra control and potency allow him to heal life threatening wounds with great speed. He can also use his medical knowledge offensively, such as creating blades of chakra or poison clouds.
Applying the chakra control of medical ninjutsu, Itami is able to use his chakra to enhance his body. He can use much more than simple chakra enhanced strength, he can also enhance his speed, durability, and even his thought. His chakra enhanced strength is more potent than Tsunade's own, which makes it extremely devastating, especially since his natural strength is also much higher. Using Chakra Enhanced Speed he is able to move faster than the eye can see, especially when combined with the body flicker. His enhanced durability allows shuriken and kunai to simply bounce off his skin, and his enhanced thought allows gives him reaction time akin to the Sharingan.
Overall, Itami possesses incredible knowledge of ninjutsu, and knows countless techniques, similar to his clansman Hiruzen Sarutobi. Also, he is able to decipher the technique his opponent is about to use simply by looking at the hand seals they're using.
Itami has the fuinjutsu knowledge of an Uzumaki, and can easily seal away powerful beasts and the like. This was shown when he was able to not only break the seal Hidou was kept in, but then immediately seal the demon into himself. He can do much more with seals as well, such as absorbing chakra, disrupting the chakra system, or simply creating barriers to trap people in. He also uses seals to store hundreds of weapons, which he can unseal and use at any time he wishes.
Itami is skilled in the use of Taijutsu as well, as training the body is key to expanding chakra reserves as well. Itami practices the Strong Fist fighting style. As such, he has incredible Strength and Speed, as he has trained extensively. He's able to shatter massive boulders with his bare hands or punch straight through steel, and his prowess in the Body Flicker Technique outstrips the likes of Shisui Uchiha. This makes him incredibly deadly in close combat, since he can subdue or kill most opponents with a single strike, before they could even see him coming.
When using his various chakra enhancers, this is even more true. His reaction time is on par with a sharingan, and he can easily predict incoming attacks and even copy them with his Chakra Enhanced Thought. His Chakra Enhanced Speed combined with his immense skill in the Body Flicker Technique makes him near impossible to keep up with, let alone react to. He can launch dozens of strikes in the blink of the eye. Plus, with his Chakra Enhanced Durability, unenhanced melee attacks will likely hurt his opponent more than they do Itami himself. This is even more true when he activates Sage Mode, which makes him a complete monster physically.
The Sages of the forest where Itami learned Sage Mode practiced a certain kind of Taijutsu as well. This was taught to Itami, and the style emulates the movement of a monkey. This fighting style focuses heavily on agility, and incorporates large amounts of flips and acrobatic movement. Using this agility along with the strength and speed granted to him by his Strong Fist training makes him incredibly dangerous, and hard to hit. Additionally, like Frog Kata, this fighting style allows the user to surround themselves in Natural Energy, allowing them to land blows that would have otherwise been dodged.
Itami has mastered the use of Sage Mode. Hidou, the demon sealed within Itami, is able to passively absorb Natural Energy like those of Juugo's Clan. Hidou however, is able to handle and store it just fine unlike that clan, and with Itami's control over the demon, Itami can have the natural energy transferred to his own body whenever he wishes. This allows him to go into Sage Mode instantly, and stay in it basically indefinitely if he so wishes. Itami's Sage Mode makes basically all his other abilities stronger, giving him tremendous power, as he's already far above most Shinobi even without Sage Mode. Additionally, Itami can use an enhanced version of Sage Mode, which he calls Demon Chakra Sage Mode. This amplifies Sage Mode's power exponentially by using Hidou's chakra, but Itami doesn't like using it often as it makes him slightly more vulnerable to Hidou's influence.
As an extension of his Senjutsu, Itami has learned a powerful Nintaijutsu style called Mage Arts. This style allows the user to use the five elements of an extension of their own body. This works by surrounding his own body in natural energy, which he can then flow his elemental chakra through, and use as an extension of his body. This effectively allows him to use strong elemental attacks with no hand seals at all. In addition, Itami has developed an application for the Mage Arts that allows him to surround his body in an aura of any element of his choosing, letting him negate elemental ninjutsu like the Yata Mirror.
Itami is able to sense the chakra of others. Itami's sense is quite precise, as he can recognize the chakra of those he's sensed before, remembering it exactly. He's able to judge the power and amount of chakra easily as well. His range is also quite impressive, being slightly shy of Karin's Eye of the Kagura technique.
When in Sage Mode, his sensory skills are greatly increased, expanding his range dramatically.
Itami also possesses skill in genjutsu, as he is able to cast a genjutsu which is able to put his opponents into complete darkness. This genjutsu is also basically impossible to break out of without dojutsu, or someone else to break you out. He can also create false surroundings, or make his opponents see nightmarish things. He also can use a genjutsu involving a blade, causing his opponent to see the blade multiple times, disorienting them. Additionally, Hidou is able to break Itami out of genjutsu as a Tailed Beast would.
Itami is quite skilled in Bukijutsu as well, as all shinobi should be. Due to his Chakra Enhanced Thought, Itami is able to throw shuriken and kunai with incredible precision, since it allows him to process information faster and predict movement paths. This also allows him to hit things that are in his blind spots, as Itachi Uchiha could with his Sharingan. Combined with his knowledge of medical ninjutsu, Itami is able to cause fatal blows with a single shuriken or kunai, or strike with enough precision to non-fatally paralyze an opponent. Itami is also able to enhance his weapons with any of the five basic nature transformations, allowing them to move faster, cut and pierce with more power, or even paralyze or burn his opponents. Itami utilizes the Shuriken Shadow Clone technique to create thousands of weapons from a simple handful, allowing him to overwhelm opponents with sheer numbers, and also allows him to keep minimal weapons with him.
Itami, during his travels around the world, witnessed the Samurai's kenjutsu style, and copied it for his own use. Using this fighting style, Itami is able to strike instantly, before opponents are even able to draw their own weapons or create hand signs for jutsu. He can also coat his blade in chakra, allowing him to elongate his blade farther than usual, or form the chakra coating the blade into different shapes and weapons. Additionally, he is able to combine this with lightning release or wind release, to create large chakra weapons with greatly enhanced cutting power. Also, all the ways he can enhance shuriken, he can enhance his sword with as well.
One of Itami's most important qualities is his ability to learn new abilities with incredible speed. He was able to master all five basic chakra natures with this talent, quite an impressive feat for someone who doesn't even possess a Kekkei Genkai. This combined with his Chakra Enhanced Thought, allows Itami to even copy Hiden techniques by simply gazing upon them being used.
Also, Itami possesses incredible willpower. This along with his overall strength are what allows him to resist Hidou's influence and stay in control of his body.