Shisui Uchiha

, renowned as, was a shinobi from Konohagakure's Uchiha clan.

Background
Born into the Uchiha clan, Shisui was noted to be one of the most talented members of the famed clan. At some point in the past, he fought with Ao of Kirigakure who retained an acute memory of Shisui's chakra colour, as well as the Uchiha's ability to control others with his Mangekyō Sharingan's ability.

When Shisui's best friend, Itachi Uchiha, began to act "oddly", Shisui was instructed by the Konoha Military Police Force to monitor Itachi because the younger Uchiha's position in Anbu was instrumental to the Uchiha's future status in Konoha. As the Uchiha continued to grow angrier and more violent from the distrust of the village due to the suspicion of their involvement from the Nine-Tails' Attack on Konoha, Shisui was perplexed that the clan would not deter from the coup d'état that they were planning and Shisui was greatly concerned with the consequences that would follow their actions. Shisui approached the Hiruzen Sarutobi revealing the truth to the Third Hokage. Trusting Shisui, Hiruzen allowed the Uchiha to spy on his clan for the village. Ultimately, it was decided that Shisui would use his Kotoamatsukami on Fugaku Uchiha to subtly end the coup d'état plan. Later, as Shisui prepared to make his move, Danzō Shimura, believing that simply manipulating the Uchiha's leader wouldn't end the conflict, chose to take Shisui's eyes for himself in the desire to protect the village in his own way. While Shisui effortlessly subdued Danzō at first, the ruthless elder caught Shisui off guard with the forbidden Izanagi, allowing Danzō to steal Shisui's right eye. As Danzō and his men surrounded Shisui to take the left eye, Shisui managed to escape.

Fearing that Danzō was right in Shisui's inability to stop the Uchiha's revolt and that the elder would continue to pursue his left eye as well, Shisui entrusted it to Itachi, telling him to protect both the village and the Uchiha name. In order to prevent conflict from arising over his eyes within the clan, Shisui wrote a suicide note and made it appear as though he had crushed his eyes when jumping off a cliff into the Naka River to kill himself. He, at the same time, was able to erase his existence, leaving no corpse behind.

Personality
Itachi was Shisui's best friend; in fact, Itachi thought of him as a brother. Shisui taught Itachi that "self-sacrifice… a nameless shinobi who protects peace from within its shadow…" was the true mark of a shinobi. Shisui was also very devoted to the clan, which is why the Konoha Military Police Force asked him to spy on Itachi. It is because of this devotion that the police did not believe he could have committed suicide.

Although Shisui was devoted to his clan, he was even more devoted to the well being of his village. His devotion to his village was so strong that he never fell victim to the Curse of Hatred when awakening his Sharingan or even his Mangekyō Sharingan. He even went as far as to attempt to put his clan under a genjutsu in order to stop their coup d'état which would lead to civil war. However, this failed when Danzō stole his right eye. Knowing Danzō's power hungry personality would eventually lead him to steal his left eye as well, he resolved to prevent Danzō from stealing it to prevent him from gaining too much power. With this in mind, he entrusted his left eye to Itachi and told him to protect the village and was able to die with a smile knowing the village would be in good hands despite all he had been through prior to his death. Shisui even went as far as to erase his own existence to prevent his corpse from falling into the wrong hands, which inadvertently, prevented him from being reincarnated by Kabuto years later and being forced to fight his own village. According to Itachi, he and Naruto Uzumaki hold similar ideals and goals.

Appearance
Bearing stark resemblance to his father, Shisui also had short, unkempt, dark-coloured hair and a relatively broad nose and well-defined eyelashes, that were turned upwards at each end. In the anime however, these lines are broken instead of whole. He wore the standard attire of the Uchiha clan which includes a high-collared, dark-coloured outfit along with a tantō strapped to the right side of the back of his shoulder. He also wore what appeared to be a harness for his tantō which ran across his chest and fastened over both his shoulders. During his time in the regular forces, Shisui donned the standard Konoha attire.

Abilities
Shisui was noted to be one of the most talented members of the Uchiha clan. He had earned the nickname of "Shisui of the Body Flicker" as he had great mastery of the Body Flicker Technique. Shisui often made practical uses of the Body Flicker Technique to appear before Itachi to signal a private meeting between them and quickly disappear without anyone else even catching a hint he was ever there. His abilities also made him a captain of his own squad. Likewise, an entire squad of Kiri-nin quickly chose to fled upon learning of his presence. A further testament to his prowess is that Kabuto Yakushi wanted to reincarnate him for the war but failed to find sufficient DNA samples. He also displayed a high level of pain tolerance, as he didn't flinch from ripping out his own left eye to give to Itachi. He wielded a tantō which he was presumably adept at using.

Nature Transformation
As it is traditional to the Uchiha Clan, Shisui was an adept user of Fire Release techniques, specifically the rite of passage Great Fireball Technique. Shisui's usage of the technique required the efforts of many Anbu-level Water Release users to counterbalance it.

Sharingan
Like many members of his clan, Shisui was a wielder of the Sharingan. Alongside his friend Itachi, he was praised for superior skill, mastery, and sheer power in its use. Using it, he gains access to the dōjutsu's generic abilities such as seeing chakra, predicting movements, and placing a victim under paralysis genjutsu with just a single glance. Hailed as the most powerful genjutsu user of the clan, his genjutsu prowess were powerful enough to even trap other powerful users of the Sharingan, like Danzō, forcing the latter to resort to using Izanagi. Shisui was also able to trap multiple individuals in his genjutsu from great distances away.

Mangekyō Sharingan
Shisui was one of the few members in the clan's history that was able to awaken the Mangekyō Sharingan. Its design is a four-point pinwheel and granted him access to powerful genjutsu techniques, the strongest of which was a unique genjutsu noted to be of the highest calibre, Kotoamatsukami. This technique allowed him to enter a person's mind and manipulate them by giving them false experiences, making it seem as if they were doing things on their own free will; the victim wouldn't even notice they were being manipulated.

This ability was so unique and powerful, that even Obito wanted it for himself and was angry that Danzō managed to destroy the eye before he died. Kabuto was also extremely thrilled when he learned that the remaining eye was within Itachi's crow. Shisui's eyes were also seen as something of a treasure even within his own clan, as before his death he had to ensure that it looked like he had destroyed them before he had died, fearing it would end in conflict otherwise.

Legacy
Throughout his lifetime and even in death, Shisui influenced Itachi greatly as a friend in teaching him self-sacrifice and how a true shinobi must protect his village from within its own shadow. This possibly influenced Itachi in his future actions to the staving off of a possible civil war within the village that may have escalated into a world war. Shisui's effort to erase his very corpse was successful as even Kabuto Yakushi noted that he was unable to locate it in an effort to reincarnate Uchiha for the Fourth Great Shinobi War. Despite leaving a note, claiming that he was tired of carrying out the clan's duties, the police suspected that Itachi had murdered him and used his Sharingan to forge the suicide note, since suicide was very unlikely for someone of Shisui's character. Using Shisui's death to his advantage, Itachi later told Sasuke Uchiha that he did kill Shisui and forged the suicide note to awaken his Mangekyō Sharingan, all in an effort to motivate Sasuke to kill him as repentance for his crimes.

Even years after his demise, Shisui's powers and actions left their mark on the world. While Danzō used the eye he stole for his questionable agendas to maintain their village, Itachi kept Shisui's other eye to honour his friend's final request to protect the village and their clan's good name. Inserting the eye in the body of a crow, Itachi made final arrangements to implant the bird in Naruto's body as a countermeasure against Sasuke if he learned the truth behind the Uchiha clan's demise and attempted to destroy Konoha.

However, due to the immense power that Shisui's eyes held, they were eventually destroyed to prevent them from falling into enemy hands: Danzō destroying his eye in his final moments to keep Tobi from acquiring it, and a reincarnated Itachi, after Kotoamatsukami was used on him, incinerated the crow. But Itachi also stated that above all else, Shisui wanted someone to inherit his will and ideals, believing Naruto to be that someone.

Trivia

 * Shisui's name has two interpretable meanings. Combining the words and, Shisui would mean "death water", which is a reference to his death by drowning.  alone means "still water" or "stagnant water".
 * While it was said that Shisui is Kagami Uchiha's, their exact relationship is unknown.

Quotes

 * (To Itachi) "…You're my best friend and the only one I can count on… Protect the village… and the Uchiha name."