The Mangekyo Sharingan is an advanced form of the Sharingan that has only been Fully activated by a handful of Uchiha.
They are noted to be the heavenly eyes that see the truth of all of creation without obstruction.
A Mangekyo Sharingan is distinguished from a normal Sharingan by its appearance, which changes the form of the tomoe seal. The exact design differs for each user, though all resemble pinwheels. It is at the beginning awakened by the trauma suffered from witnessing the death of someone close to the user. all Uchiha have historically misunderstood this criterion as the user needing to be responsible for the person’s (Friend) death, and for that reason, they developed the practice of killing their closest friends in order to gain the Mangekyo Sharingan. Obito’s Mangekyo activated immediately after his trauma, whereas, in Naruto Jinraiden, Sasuke’s Mangekyo didn’t activate until several weeks afterward.
Eternal Mangekyo Sharingan. The Eternal Mangekyo merges the designs of the transplanter and the transplantee’s original Mangekyo. Their Mangekyo based abilities are made stronger and they no longer suffer any negative side effects from the usage. According to Madara, the Eternal Mangekyo Sharingan is proof an Uchiha continues to seek something despite experiencing great losses. Should the eyes evolve to this state, the user will keep all their previous techniques from their original eyes. In addition to the unique techniques, the straight tomoe form of Madara’s and Sasuke’s Eternal Mangekyo Sharingan grants them fluidity in their movements when fighting.
1 – Itachi Uchiha
Itachi Uchiha awakened his Mangekyo Sharingan after witnessing the suicide of his best friend, Shisui Uchiha, shortly before the Uchiha Clan Downfall. With his left Mangekyo, he can use the Tsukuyomi, an extremely powerful genjutsu that distorts the victim’s sensibility of the time. With his right Mangekyo, he can use the Amaterasu, creating inextinguishable black flames at the user’s focal point. Because he awakened both his Mangekyo, he can use Susanoo. Use of the Mangekyo is particularly debilitating for Itachi Uchiha, such that after using it three times in one day he can no longer Use his normal Sharingan active. Sometime after Itachi’s death, desiring the power to kill Naruto Uzumaki, Sasuke had Itachi’s eyes transplanted into him.
2 – Obito Uchiha
Obito Uchiha awakened his Mangekyo Sharingan after the death of Rin during the Third Shinobi World War; Obito Uchiha himself only had his right eye at the time, but the event caused his Mangekyo to simultaneously awaken in Kakashi Hatake, who wielded Obito’s left eye. Both eyes have access to Kamui, able to teleport the targets to and from Kamui’s Dimension though in different manners. The right eye is able to use close-range Kamui, teleporting the user or those they’re in contact with. By teleporting only Body parts of their body there, they can in effect seamlessly pass through other matter. The left eye is able to use the long-range Kamui, creating a barrier around the target that teleports them. The left eye can also target the user themselves. During the 4 Shinobi World War, it was discovered that each eye is impervious against the others’ Kamui.
Madara Uchiha steals Kakashi Hatake’s eye in order to pursue Obito to Kamui’s dimension. There, he exchanges the eye for Obito’s Rinnegan, returning both eyes to their original owner, who was currently possessed by the Black Zetsu. During this brief period, the Black Zetsu also gained access to both Sharingan powers. After Obito was freed from Black Zetsu’s control, he uses them in combination effectively thereafter, but the eyes are destroyed when he is killed by Kaguya Otsutsuki’s All Killing Ash Bones. His spirit briefly returns to the living plane and inhabits Kakashi, giving him both Mangekyo’s with their respective abilities and, by extension, Susanoo.
3 – Madara Uchiha
Madara was the first Uchiha to awaken the Mangekyo Sharingan. Madara not known what the individual abilities of each of his eyes were, but he was able to use Susanoo. When Madara’s over-usage of his Mangekyo during the Warring States Period left him blind, this prompted his brother, Izuna, to bequeath Madara his eyes on his deathbed for the sake of preserving the Uchiha, thus granting Madara the Eternal Mangekyo Sharingan. The straight tomoe of his Eternal Mangekyo Sharingan granted him fluidity in his movements when fighting.
Towards the end of his life, Madara Uchiha was able to evolve his eyes into Rinnegan, which he transplanted to Nagato Uzumaki when Nagato was a child without anybody ever knowing. The eyes eventually found their way back to Madara Uchiha after he is revived.