Amaterasu

Named after the Shinto Sun Goddess, Amaterasu is the highest level Fire Release technique, as well as one of the most powerful ninjutsu in existence. It is said to represent the, the antipode to Tsukuyomi, a genjutsu of similar power and a fellow Mangekyō Sharingan dōjutsu, said to represent the. Itachi Uchiha was the first person to be shown to be able to use Amaterasu. He later gave the power to Sasuke Uchiha.

The jet-black flames of the Amaterasu are said to be as hot as the sun. The flames are extremely powerful, capable of burning through Jiraiya's Summoning: Toad Mouth Bind, which Jiraiya stated to be fire resistant. It can even smother regular flames easily. Not surprisingly, it appears to use a large amount of chakra. However, despite the power of the flames, they seem to burn incredibly slowly. For example, it took quite some time to get E's hand completely immolated, there was also time to save the samurai who was hit by the Amaterasu before the flames burned completely threw his armor, as well as put the flames out on Karin's back before they could burn into her skin. On the other hand, when Itachi used it to burn through the Toad Mouth Bind and Sasuke, it seems to have burned rather fast, and Sasuke barely have enough time to shed his skin to evade before it was incinerated. The flames are said to burn for seven days and seven nights, and cannot be extinguished with water or any other normal methods. However, it can be extinguished by the user's alternate eye. Jiraiya had also managed to seal some of the black flames with the Fire Sealing Method.

Though said in the data book to burn everything reflected on its retina, Zetsu also commented that Amaterasu burns everything within Itachi's wide field of vision to cinders with an unholy black flame, to the degree of being able to burn an entire forest or village with it. Wherever the user focuses his eye, the flames will appear at the exact spot without moving, making it unavoidable as long as the user keeps his vision trained on the target. However, the delay in which it is launched makes it possible to evade, as the Fourth Raikage demonstrates using his Body Flicker Technique, due to his speed being greatly amplified by his Lightning Release Armor.

During the battle between Itachi and Sasuke, after Sasuke escaped Tsukuyomi, all genjutsu between the brothers became pointless. Itachi was forced to shift from his most powerful genjutsu to his most powerful ninjutsu. As opposed to Tsukuyomi, which originated in Itachi's left eye, the Amaterasu came from his right eye. Although not shown in its entirety when used while escaping Jiraiya, in the battle with Sasuke, Itachi's eyes were strained to the point that he drew tears of blood while executing Amaterasu.

When Sasuke met Madara Uchiha, Itachi's Mangekyō Sharingan automatically used Amaterasu. Madara later explained that Itachi had implanted Amaterasu in Sasuke's eye to detonate upon seeing Madara's Sharingan.

Sasuke used his own Amaterasu whilst fighting Killer Bee. Like Itachi's, his eyes began to bleed as well. Opposite to Itachi, Amaterasu comes from Sasuke's left eye. However, Sasuke's usage of Amaterasu is much more skilled than Itachi's, as Shī commented during the fight against the Raikage. After Karin was accidentally hit with Amaterasu, Sasuke used his right eye to suppress the flames, and did the same with Killer Bee. Sasuke has also shown the ability to manipulate Amaterasu to such an extent that he is able to form a full-body shield around himself, in combination with Susanoo to protect himself from the flames. Both feats are not shown by Itachi. Sasuke's excellent control of the black flames has even allowed him to use them to develop his own element, the Blaze Release.

Influence
As from the ancient Japanese myth of Amaterasu, Tsukuyomi, and Susanoo, when Izanagi washed his face after escaping the underworld his left eye became the Sun Goddess, Amaterasu.