Susanoo

Susanoo, also known as the, is the third ability granted by the Mangekyō Sharingan to those who awaken the abilities: Tsukuyomi — which symbolises the "darkness of the spiritual world" and Amaterasu — which denotes the "light of the material world". It creates a gigantic, humanoid being that surrounds the user. As one of the strongest techniques granted to those that have acquired the Mangekyō Sharingan, it is the user's guardian deity. Those whom have Eternal Mangekyō Sharingan-evolved Rinnegan are able to use their Susanoo freely.

Overview
For a Sharingan user to activate the Susanoo is a rarity. Like the other techniques granted by the Mangekyō Sharingan, the user's eyes and body are strained while using Susanoo because it consumes a large amount of their chakra. Sasuke described it as feeling pain in every cell in his body which only grew from prolonged use. Susanoo is formed through the materialisation of the user's chakra and as such differs in appearance, as well as colour between users. Even though it envelopes the user, they can move around within Susanoo freely, use techniques from inside of it, as well as manifest parts of Susanoo — as the situation calls for it.

Despite Susanoo's impressive defensive capabilities, the protection it grants its user is not absolute. The user can be thrown out of the upper half of Susanoo by an enemy manipulating the substance underneath Susanoo. This was seen when Gaara used his sand to pull Madara out of his Susanoo. Also, a sufficiently powerful attack will still result in damage, especially during the technique's developmental stages. The only known ways to attack the user while Susanoo is active is either to draw the wielder out of the technique and then attack, bind and restrict its movements, or to break the defence with overwhelming force. Susanoo users are also vulnerable to attacks which don't actually deal physical damage to it, such as strong lights and sounds, that can also impair their ability to sustain Susanoo. Sound-based genjutsu can also bypass Susanoo's impressive defence.

Development
Each Susanoo goes through several different forms, which the user can switch between at will or even leave in a state between forms. The development of these forms was best demonstrated while Sasuke was learning how to use the technique, gaining additional forms as his control over it increased. In its earliest form, users can only manifest some of Susanoo's skeleton. A smaller version of Susanoo's ribcage is generally produced first which, while providing a good defence, can still be fractured or even melted. An arm can also be formed, which is sometimes connected to this ribcage, and can then be used to interact with the surroundings. It is also possible to utilise one of Susanoo's weapons using said arm and change its size as needed. When first forming, Susanoo manifests around the user like an aura.

As users gain additional control, musculature and skin begins to appear atop of its bones, which progressively complete the full skeletal structure. It is only when Susanoo's growth is fully matured and thus, the user is completely surrounded, are the vulnerabilities of the skeletal form finally eliminated. However, it should be noted that Susanoo can also appear behind the user, instead of just surrounding them. The user can also change the size of it to fit the current situation. Eventually, Susanoo develops into a "complete" warrior-like form, where its skin, armour and final arsenal of weapons are manifested in their entirety. At this stage, it can anchor the user to the ground, preventing opponents from forcibly moving them unless they can get through Susanoo's various layers. In its final form, this fully humanoid shape is further surrounded by a secondary layer of armour that causes Susanoo to resemble a yamabushi.

Influence

 * Similar to other Mangekyō Sharingan abilities, Susanoo was taken from Japanese mythology: Susanoo is the wild god of sea and storms, brother to Amaterasu and Tsukuyomi. He was born from Izanagi washing his nose. Susanoo inherited his father's sword Totsuka no Tsurugi, which Izanagi used to kill his newborn son, Kagu-Tsuchi after his birth burned his mother, Izanami, to death. After his exile for his relentless harassment of Amaterasu, Susanoo redeemed himself when he used Totsuka to slay the serpent Yamata no Orochi and obtained the Sword of Kusanagi from the monster's corpse. He later gave the acquired blade to Amaterasu as a peace offering.
 * Susanoo's designs are based on, well known yokai that are associated with the ascetic practice of shugendō. In their final forms, the Susanoo are garbed in the attire of shugendō practioners, known as yamabushi, and wear hoods that resemble tengu masks, with Itachi's and Madara's appearing as long-nosed Hanataka Tengu and Sasuke's as a crow-billed Karasu Tengu. In Japanese myth, Susanoo produced the fiend Amanozako who is said to have been the progenitor of the Tengu.