Susanoo is a technique that creates a spiritual humanoid being. The spirit is gigantic and surrounds and protects the user. It is the third ability granted by the Mangekyō Sharingan, after Amaterasu and Tsukuyomi have been awakened. According to Madara Uchiha, for a Sharingan user to activate the Susanoo is a rarity. Like the other techniques granted by the Mangekyō Sharingan, the user is strained while using Susanoo because they must act as a medium for the spirit, allowing it to consume their life force energy. Sasuke describes it as feeling pain in every cell in one's body, and while Itachi was close to death, it slowly deteriorated. Both Itachi and Sasuke are able to summon the spirit, though they differ in appearance. They both begin by forming a large skeleton with muscle tissue around the user. Even in an imperfect state, the bones can act as armor for the user and it is capable of regenerating as long as the user has the energy to spare.