Susanoo

Susanoo is a gigantic, humanoid being made of the user's chakra that surrounds them and fights on their behalf. It is the strongest ability available to those who have the Mangekyō Sharingan, though it is said to be rare to achieve. In order to use this ability, the wielder must have awakened the Mangekyō Sharingan in both eyes.

Attributes
When activated, Susanoo forms around the user and becomes an extension of their will, acting and attacking on their behalf. By default, Susanoo is anchored to its user and they to it: in its less developed forms it will move around with the user; in its more completed forms the user will be suspended within Susanoo, being brought with it as it moves around. This connection allows Susanoo to shield against physical attacks, one that becomes more difficult to penetrate as it is manifested more fully. If it is damaged, Susanoo does not regenerate and it can only be repaired either by advancing it to the next developmental stage or by dispersing it and then forming it anew.

Although Susanoo is quite effective as a defence, it is able to distinguish in what it blocks. For example, the user can still perform jutsu while within Susanoo and the attacks will pass through it without complications. Others can be brought within Susanoo with the user's permission, and users can likewise choose to leave Susanoo's protective envelope. The latter property can be used against the user, as if an opponent can bypass Susanoo, however slightly and latch onto them, they can be pulled out of Susanoo. With continued mastery, Susanoo can have increased defensive capabilities even at its ribcage stage, as seen when A was able to break through Sasuke's Susanoo, but could not even crack Madara's. Susanoo is also only able to defend against physical attacks, so they are still vulnerable to visual or auditory attacks.

So long as it is active, Susanoo draws on the user's chakra in large amounts. Sasuke Uchiha describes the sensation of using Susanoo as feeling pain in every cell in his body, which only increases over time and at higher developmental stages. Being a Mangekyō Sharingan-based ability, it also places a strain on the user's eyes the more it is used. However, it is not actually necessary for one's Mangekyō Sharingan to be active while using Susanoo; in fact, Madara Uchiha is able to use it without any eyes at all.

Development
As seen with Sasuke's learning how to use it, Susanoo has several developmental stages. Practised users go through all the stages every time they manifest it, layering more advanced stages over earlier ones or stripping them away as is needed; they can choose to stop at any developmental stage along the way if they choose to. At its simplest level, users only manifest aspects of Susanoo's skeletal structure, such as a ribcage for basic defence or an arm for interacting with the surroundings. Once a full skeleton is made, musculature and, later, skin forms until finally a complete humanoid is shaped. In these early stages, typically only the upper half of Susanoo is materialised, with legs becoming common once it reaches its full humanoid form; however, not all Susanoo users can accomplish the latter feat.

Users are able to mingle the chakra that makes Susanoo with chakra from other sources. Sasuke uses the chakra from Jūgo's Sage Transformation to make a, with markings reminiscent of the Cursed Seal of Heaven spreading across it. He later stores the chakra of the nine tailed beasts within his Susanoo, drastically improving its strength and causing lightning to emanate from its back.

Versions
Susanoo differs between users, varying in terms of colour, armour design, and weaponry used. All Susanoo wield at least one sword, though the type of sword varies.

Itachi Uchiha
Itachi Uchiha's Susanoo is yellow in the manga; in the anime, its skeletal and armoured forms are red and its humanoid form is orange. In its humanoid form, its face is framed by locks of hair, with an appendage on its chin reminiscent of a Pharaoh's false beard. When its armour is formed, Itachi's Susanoo resembles a long-nosed tengu and it wears a pair of magatama earrings.

Itachi's Susanoo possesses a curved blade that resembles a dagger or tantō. He rarely uses this, however, preferring his Sword of Totsuka, wielded in its primary right hand and sheathed in a sake jar held by its second right hand. The Sword of Totsuka is an ethereal weapon with an enchanted blade that, in addition to standard cutting, can seal anyone it pierces, trapping them in a genjutsu-like "world of drunken dreams" for all eternity. In its primary left hand, Itachi's Susanoo wields the Yata Mirror, a shield that can change its nature depending on the attack it receives, thus nullifying it. According to Black Zetsu, the simultaneous use of the Sword of Totsuka and the Yata Mirror made Itachi essentially invincible. For long-range attacks, Itachi can use Susanoo to perform Yasaka Magatama.

Sasuke Uchiha
Sasuke Uchiha's Susanoo was initially depicted as a dark shade of blue in the manga, though it is purple in all other medias. Because Sasuke's development has often been marked by intense feelings of hatred, his Susanoo is noted to be much darker in composition compared to Itachi's. Whereas Itachi's Susanoo appears relatively "normal", Sasuke's possesses demonic horns, a long appendage on its chin, and a malevolent grin. Its armoured form initially appears largely the same as Itachi's save for having jagged teeth around its hood. After Sasuke gains the Eternal Mangekyō Sharingan, however, its appearance changes, the armour's mouth taking on a beak-like shape and generally becoming ghastly-looking.

Sasuke's Susanoo has a blade in all its forms: a sabre in its developmental forms; an Ōdachi in its humanoid form, wielded with its second right hand; a pair of katana in its Complete Body form. Its primary weapon, though, is a bow, manifested on the wrist of its left arm; the bow can double as a shield, a function that becomes more visually apparent in its armoured form. Arrows are drawn from an orb held by its primary right hand and can be fired very quickly, such that only Kabuto Yakushi, while utilising Sage Mode, has been able to avoid one. The arrow's properties can be augmented with black flames in its armoured form.

Madara Uchiha
Madara Uchiha's Susanoo is blue in colour. His Susanoo is made up of two entirely different sides that are conjoined along their spine, both of which have a distinct face: the front face has elongated canine teeth in its lower jaw bracket and two tusks growing from said jaw, while the back face has similarly elongated canine teeth in its upper jaw bracket and a single horn protruding from its forehead. In its armoured form, the usual tengu-like armour splits from its forehead down, revealing Susanoo's eyes while obscuring the rest of its face. Curiously, his armoured Susanoo appears to always form the Tiger hand seal with its front hands, and is the largest of its variation.

Madara's Susanoo wields distinct, undulating blades that resemble kris, held in the right hand of each side. He is able to throw the blades as guided projectiles. In the anime, Madara was able to manifest swords in all four of Susanoo's arms; the blades left traces of blue, fire-like chakra in the ground after impacting and could unleash shockwaves capable of obliterating numerous shinobi in a single strike. For long-range attacks, Madara can use Susanoo to perform Yasaka Magatama.

Shisui Uchiha
In Ultimate Ninja Storm Revolution, Shisui Uchiha can use a green Susanoo, even after Danzō stole his right eye. It has blade-like appendages on its shoulders, the side of its face, and along its forearms. Its right arm wields a drill-like lance that Shisui can coat with fire to create a vortex of flames. It is also able to unleash a barrage of chakra needles.

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.
 * Madara's Susanoo design may be influenced by, a human-like being described in the as having one body with two faces back-to-back, each with its own set of arms and legs.
 * The is one of the, together with the Sword of Kusanagi and the.
 * Itachi's Susanoo carries the Sword of Totsuka in a gourd. An ethereal weapon inside a gourd could be a reference to the hyōtan-kozō, a gourd spirit from Japanese folklore.

Trivia

 * In the anime, Sasuke's armoured Susanoo before acheiving the Eternal Mangekyō is depicted identical to Itachi's, even wielding weapons identical to the Sword of Totsuka and Yata Mirror. Its appearance and weapons were changed to match the manga in subsequent appearances.
 * The third databook states that the user must first unlock Tsukuyomi and Amaterasu before they can gain Susanoo, though this was only the case for Itachi. In the fourth databook, acquiring this technique is done through the user manifesting both Mangekyō Sharingan.
 * Prior to the completion of Sasuke's Susanoo, its humanoid form was glimpsed as a shadowy figure in a genjutsu he used.
 * Sasuke's humanoid Susanoo bears a great resemblance to Raideen the Brave, one of a number of Yoshiyuki Tomino references in the series (another being the Gundam-derived names of Kakuzu's techniques).
 * Shisui's Susanoo resembles the eponymous mecha from the anime Steel Jeeg.
 * In Ultimate Ninja Storm 3, Madara's Susanoo swords are capable of spinning, giving them a drill-like ability.
 * In Ultimate Ninja Storm 4, Itachi and Shisui's Susanoo are given Complete Body — Susanoo forms, designed by Kishimoto himself, making it so all known Susanoo users have access to its highest form across different media. Also in the game, Madara's Limbo clones possess the ability to use Susanoo, while Madara himself, empowered as the Ten-Tails jinchūriki, was shown using a larger form of the Complete Body — Susanoo.