Izanagi

Izanagi is a Sharingan dōjutsu which the Uchiha clan deemed forbidden. According to Madara Uchiha, it is the most powerful genjutsu an individual can cast upon themselves. When activated, the caster removes the boundaries between reality and illusion within their personal space. This allows the user to control their own state of existence. The actual effects of Izanagi varies from user to user, but seem to involve the ability to deem negative events an illusion and positive events a reality, in regards to themselves.

When Izanagi is activated, it is capable of turning injuries and even death inflicted upon the user into mere illusions. Whenever the user receives a fatal injury, their body fades away as a genjutsu. The user's body then returns back to reality, unscathed and physically real. Danzō, in an effort to make practical use of the jutsu, had ten Sharingan eyes embedded onto his right arm. This allows Danzō to increase the length of time that Izanagi can stay active. However, not being of Uchiha blood, this technique requires substantial amount of chakra for Danzō to use, which is made possible only by the transplant of Hashirama Senju's DNA to increase his energy.

Though the sustained time of the jutsu can greatly differ between individuals, Danzō is implied to have had Orochimaru forcibly extend the time it takes for each eye to close to as long as 60 seconds. After the aforementioned time, the eye used to activate Izanagi will permanently close and be stricken with blindness, forever. It is this side effect of Izanagi that caused the Uchiha to label the technique a kinjutsu.

It is quite possible Madara Uchiha used this jutsu in his battle with Hashirama Senju, thus explaining how he was able to fake his death and why he covers his left eye.

Influence
Like the various jutsu gained from the Mangekyō Sharingan, this jutsu is named after a Shinto kami. In this case it is Izanagi-no-Mikoto, who, together with his sister and wife Izanami-no-Mikoto, created the islands and other deities of Japan.

One of the most famous stories about Izanagi-no-Mikoto tells the tale of how he goes into Yomi, the Japanese underworld, to retrieve Izanami-no-Mikoto after she died giving birth to the Shinto fire god Kagutsuchi-no-Kami. After he fails to retrieve her and leaves Yomi again, he washes himself in a stream. As he cleans his left eye, Amaterasu-Ōmikami is born, as he cleans his right eye, Tsukuyomi-no-Mikoto is born, and as he cleans his nose, Susanoo-no-Mikoto is born.