Mangekyō Sharingan

The, noted to be the , is an advanced form of the Sharingan that has only been activated by a handful of Uchiha. It was also awakened by Kakashi Hatake — a non-Uchiha.

Overview
The Mangekyō Sharingan is awakened through the trauma experienced from the death of a person very close to the Sharingan user. With the user normally having to witness or experience this first hand, Uchiha throughout history have killed those closest to them in order to expedite this process. To obtain the Mangekyō Sharingan, one must feel the emotion of losing a friend or family, as merely killing them or watching them die will not activate it.

It is distinguished from a normal Sharingan by its appearance, which changes the form of the tomoe seal. Unlike the Sharingan, the appearance of the Mangekyō Sharingan differs from user to user with all known wielders of the dōjutsu having eyes that resemble variations of pinwheels; one variation is a rare form known as the, which seems to grant the user fluidity in their movements when fighting.

The Mangekyō Sharingan gives the user enhanced power of the Sharingan's generic abilities and each eye can also awaken different powerful techniques. Some wielders awaken the same technique in both of their eyes, such as Obito and Shisui Uchiha. Also, a Mangekyō Sharingan can transfer any of its techniques into another eye and set them to activate at certain times with pre-programmed actions, even after the user's death. The Mangekyō Sharingan drains a considerable amount of chakra and strains both the user's eyes and body, a drawback which affects a non-Uchiha even more so. Use of the dōjutsu gradually deteriorates the user's eyesight to the point of blindness; a harsh fate for those that have grown accustomed to the power and visual acuity it affords.

Only by transplanting the eyes of another Uchiha can the user regain their sight and ocular powers. By transplanting the Mangekyō Sharingan of an Uchiha with strong blood ties to the recipient — ideally a sibling — an can be created. This process takes several days for a complete recovery, and not only permanently restores the recipient's eyesight, but also bolsters their own ocular power with that of the donor's, signified by the intertwined appearance of their Mangekyō Sharingan's tomoe seals. Due to the compatibility issues and the Mangekyō Sharingan's rarity, not everyone can gain these benefits by transplanting the eyes of just any Uchiha, which has been the cause of many fruitless sacrifices throughout the Uchiha clan's history. Thus far, only Madara and Sasuke are known to have been successful in this endeavour.

Madara and Sasuke were able to evolve their Eternal Mangekyō Sharingan into the Rinnegan Madara did so after implanting the DNA of Hashirama Senju into himself, though the dōjutsu only awakened years after the implant. Sasuke awakened his once Hagoromo gave him half of his power.

Itachi Uchiha
Itachi Uchiha gained the Mangekyō Sharingan after witnessing his best friend Shisui throw himself off a cliff. With the Mangekyō Sharingan, Itachi was able to use at least three powerful techniques. With his "left Mangekyō" he could use Tsukuyomi, an extremely powerful genjutsu that allowed him to distort the victim's perception of time, torturing their psyche for what seemed like days in a matter of seconds. With his "right Mangekyō" he could use Amaterasu, a ninjutsu which creates virtually-inextinguishable black flames at the user's focal point that continue to burn until the target is reduced to ash. The last of these known techniques was Susanoo, which allowed Itachi to summon a massive ethereal warrior. This entity fights on behalf of Itachi and shields him from most attacks. According to Zetsu, when it is combined with the Yata Mirror and Sword of Totsuka it essentially made Itachi invincible. Itachi's Susanoo has three forms which it goes through: an incomplete skeletal form, a complete warrior-like form and a final form that resembles a yamabushi.

Use of the Mangekyō Sharingan put a great strain on Itachi's body and would quickly deplete his chakra reserves to the point that after using it three times in a day, he deactivated his eyes to their normal state. A clone containing 30% of his chakra couldn't use it once. By the time he battled Sasuke, his sight had been reduced to a large blur, yet having resolved himself to dying at the hands of his brother, he pushed past this limitation and used his Mangekyō Sharingan more than three times as well as other techniques. After being reincarnated by the Impure World Reincarnation technique, Itachi was able to use the Mangekyō Sharingan for extended periods of time without complaints of physical ailments, or deteriorating vision. Some time after his death, Sasuke took Itachi's Mangekyō Sharingan as his own, granting the former an Eternal Mangekyō Sharingan.

Kakashi Hatake
Kakashi Hatake's Mangekyō Sharingan awakened after the trauma of killing Rin Nohara with his own hands. Despite its awakening, Kakashi only began to use the Mangekyō during Part II of the series, making it unknown if he knew he possessed it beforehand. Regardless, with this dōjutsu Kakashi can use a space–time ninjutsu known as Kamui to create a barrier and transport a target either to or from the other dimension. The barrier requires considerable effort to aim with precision, leaving Kakashi's chakra significantly drained; especially considering that Kakashi is a non-Uchiha. Initially, he could only handle two uses in a single day, left crippled for over a week from a third use, and had poor control at aiming it. However, later he could control the size of it to only affect the target he chooses, and use precise aim to warp speeding targets. He can also use it twice in quick succession, without showing immediate chakra drain and fatigue. By the time of the Fourth Shinobi World War, Kakashi became able to use it several more times in a single day, even with multiple other chakra-taxing techniques, and recover from an over-usage much quicker. His skill grew to the point that he can use this technique on himself. Madara Uchiha eventually takes this eye from Kakashi in order to use it to warp into the other dimension to retrieve his remaining Rinnegan from Obito.

Obito Uchiha
After witnessing Rin Nohara dying at Kakashi's hands, Obito Uchiha awakened the Mangekyō Sharingan in his right eye simultaneously with Kakashi, who wielded Obito's left eye. While manifesting in separate wielders, both eyes obtain the same Mangekyō designs as they are a matching set. Obito's Mangekyō Sharingan also allows him to use Kamui, able to teleport targets to its personal dimension and afterwards can teleport the target back to the normal dimension. This short-range ability however first requires Obito to make physical contact in the normal dimension with a target besides himself. In addition, Obito's right eye gives him a form of "intangibility", brought about by him teleporting portions of his body for short periods of time, no more than five minutes at a time, to the other dimension in order to avoid damage or pass through obstacles. This also provides Obito immunity from Kamui being used directly against him by another user since they both access the same dimensional space, though attacks being warped to the other dimension can bypass Obito's intangibility. He can also combine the spatial distortion of the Kamui with his Fire Release techniques to create a massive vortex of flames.

During the Fourth Shinobi World War, while Black Zetsu took complete control of Obito's body, Madara implanted Obito's original left eye given to Kakashi back into Obito. After Black Zetsu separated from Obito, the Uchiha retained both his eyes. The said eye possesses a long-range variation of Kamui, able to teleport targets within its line of sight. With both eyes working on the same target, the process works twice as fast. Also with Kamui, Obito is able to access other dimensions besides its own by synchronising with other space-time techniques. However, doing so requires much more chakra.

Madara Uchiha
Madara Uchiha, along with his younger brother Izuna, were the first Uchiha to awaken the Mangekyō Sharingan. He eventually began to go blind from overusing it, and only by taking his younger brother's eyes did he regain his sight. This also gave him an Eternal Mangekyō Sharingan which granted him even greater power and no further fear of damage to his health or sight. His Eternal Mangekyō Sharingan looks like his original one, overlapping that of Izuna's.

Madara became one of the few to awaken Susanoo. Madara has multiple forms of Susanoo ranging from individual segments, a full-bodied form, and a "final" form that is gigantic and equal in power to that of a tailed beast. He could also use his Susanoo to shape it around tailed beasts to strengthen and protect it from Hashirama Senju's control.

In the Fourth Shinobi World War, Madara stole Kakashi's Sharingan as a temporary replacement for his own left eye. Inheriting the power of Kamui from it, Madara is able to teleport targets to and from the other dimension. Soon afterwards, Madara replaced this alternate eye with his own true left eye.

Izuna Uchiha
Alongside his brother, Izuna Uchiha and Madara were the first two people in the clan to awaken the Mangekyō Sharingan. Madara later took Izuna's eyes to regain his deteriorating vision. There are somewhat conflicting accounts of how Madara acquired the eyes; some note that Izuna willingly gave up his eyes for the Uchiha clan's sake, while others believe Madara selfishly took them by force.

Sasuke Uchiha
Sasuke Uchiha awakened his Mangekyō Sharingan after learning the truth about his brother Itachi's selfless sacrifice; filled with grief from it and the role he played in his brother's death. The appearance of Sasuke's Mangekyō Sharingan is somewhat unique among those revealed thus far, which generally possess patterns centrifugally aligned along their pupils. His own spreads and converges along the edges of the irides, resulting in three intersecting ellipses that resemble an atom model.

With his "left eye" he can cast Amaterasu. It has been implied that his skill with these black flames surpasses Itachi's, as he is able to use Blaze Release: Kagutsuchi with his "right eye" to extinguish, or apply Shape Transformation to them at will. He has also shown a preference for his right eye when casting genjutsu, some powerful enough to break a target's will, and paralyse them. Danzō Shimura stated that Sasuke's genjutsu is incapable of altering the victim's perception of time, and thus is vastly inferior to Itachi's Tsukuyomi. After awakening the powers of both eyes, Sasuke became one of the rare few capable of invoking Susanoo. Sasuke's Susanoo develops in stages during various battles; he first starts using an incomplete version against the Fourth Raikage, develops a version capable of firing arrows while fighting with Danzō, and later forms a version similar to Itachi's during his battle with Kakashi.

Due to his high chakra reserves, Sasuke is able to use the Mangekyō Sharingan techniques more frequently than his brother. Sasuke can maintain Susanoo for extended periods of time, on top of using Amaterasu and Kagutsuchi several times a day along with other chakra-consuming techniques like the Chidori. Like with all other wielders, Sasuke's use of the Mangekyō Sharingan puts a great strain on Sasuke's body and eyes.

Initially, Sasuke refused to transplant Itachi's eyes to restore his vision, claiming that his views were different from Itachi's. However, after meeting Naruto again and being shocked at his determination to save Sasuke from his darkness, Sasuke decided to take Itachi's eyes so that he could kill Naruto with his full strength. His Eternal Mangekyō Sharingan incorporates a straightened, reversed version of Itachi's Mangekyō Sharingan design into the centre of his own. With his new eyes, the final form of his Susanoo takes on more ghastly features. According to Madara, the "straight tomoe" of the Mangekyō that he shares with Sasuke possesses superior movement reading capabilities, which led Madara to rule the eyes as fitting substitutes until his own eyes were returned to him.

Shisui Uchiha
Shisui Uchiha awakened his Mangekyō Sharingan at some point through unknown means. It granted him the ability to cast powerful genjutsu techniques, the most powerful of his genjutsu arsenal being Kotoamatsukami. This technique allowed him to manipulate an opponent's thoughts completely without them having the slightest idea that they were being controlled. Furthermore, this technique can be used without eye contact or even the need to uncover the eye if concealed. The only drawback of using that technique was the fact that it would render his Mangekyō unusable for quite some time. In the anime, Shisui's Mangekyō Sharingan also had the ability to manifest Susanoo. He could produce its complete form.

Shisui's eyes had such highly coveted genjutsu prowess that his right eye was stolen by Danzō Shimura while he was still alive, and in the anime attempted to steal the left eye as well. Shisui entrusted his left eye to Itachi Uchiha and told him to protect the village and the clan's name; Shisui then made it appear as though he had crushed his own eyes in order to prevent a feud over them and erased his existence, though it was thought that he was drowned by Itachi in the Naka River.

Unlike other known individual Mangekyo Sharingan techniques, Shisui's left and right eye seem to have the exact abilities while other Mangekyo Sharingan pairs have abilities differing from minor details to being in a completely different classification.

Danzō Shimura
As tension between the Uchiha and Konohagakure grew, determined to protect the village in his own way, Danzō realized that potential usage of Shisui's eyes and managed to steal his right eye. Upon implanting it into himself, Danzō obtained access to Shisui's Kotoamatsukami, using it whenever the situation seemed necessary to manipulate people to suit his interest. Danzō also retained Shisui's ability to induce Sharingan-based genjutsu without eye-contact or exposing the eye. As the transplanted eye caused much more strain to the chakra reserves of a non-Uchiha like Danzō, the elderly ninja infused some of Hashirama Senju's DNA into himself, drastically reducing the timespan between each usage of this technique. After the Five Kage Summit, as Danzō neared death from his battle against Sasuke, not wanting the enemy to wield Shisui's power, Danzō crushed the eye before dying.

Itachi's Crow
After Shisui entrusted his left eye to his best friend, Itachi implanted it into a crow. Unlike other Sharingan-wielders, this crow appeared unable to personally control its power, instead having Itachi program the Sharingan to activate in certain situations and unleash a pre-set command with Kotoamatsukami. Itachi anticipated Sasuke's potential desire to destroy Konohagakure should he learn the truth of the Uchiha Massacre. Not wanting his younger brother to walk down such a dark path, Itachi programmed Shisui's eye to react Itachi's with the command to protect the village, knowing also that Sasuke would eventually transplant Itachi's eyes to escape the blinding side-effect from over-using his own Mangekyō Sharingan, storing the crow inside Naruto for his inevitable encounter with Sasuke. After this plan failed, having a change of heart for Sasuke's best interest and not wanting the enemy to obtain Shisui's eye, Itachi incinerated the crow and dōjutsu.

Indra
Born with his father, Hagoromo Ōtsutsuki's, strong chakra and spiritual energy, Indra had his own dōjutsu, a diluted version of his father's which became known as the Sharingan. In addition to being the first to have this particular eye, he was also the first one to awaken the Mangekyō form of it and likewise to wield the devastating power of Susanoo. Much like a small handful of his future descendants, Indra was able to form a large and complete body of the ethereal protector that he could hover inside; protected from most dangers.

Black Zetsu
In the Fourth Shinobi World War, Madara, who had previously stolen Kakashi's Sharingan, implanted Obito's left eye into its original owner, who Black Zetsu merged with and had complete control over. With the power of Kamui, Black Zetsu is able to teleport targets to and from the other dimension. Upon abandoning Obito's body, Black Zetsu lost access to these abilities.

Trivia

 * In the anime, in the fight against A, the internal intersection lines of Sasuke's Mangekyō Sharingan are replaced by a circle.
 * In the anime, when Kakashi used his Mangekyō Sharingan to warp away Sasuke's Susanoo's arrows, the black and red colours became inverted.
 * The manners in which an individual gains the Mangekyō Sharingan are almost parallel to how an Uchiha awakens their regular Sharingan for the first time, since both need intense emotions to awaken them.
 * For unknown reasons, Obito Uchiha has shown no signs of deteriorating eyesight. In addition, he has shown no signs of exhaustion despite regular use of the Mangekyō Sharingan.
 * According to Madara, only he and Sasuke have the "Straight Tomoe" variant of the Mangekyō Sharingan. The two are both Indra's reincarnations, the only ones who awakened the Eternal Mangekyō Sharingan and were able to awaken the Rinnegan as well.