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 Tengu (天狗), 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 Ryomen Sukuna (両面宿儺), a human-like being described in the Nihon Shoki (日本書紀) as having one body with two faces back-to-back, each with its own set of arms and legs.
The Yata no Kagami (八咫鏡, Literally meaning: Eight Span Mirror) is one of the Three Imperial Regalia of Japan (三種の神器, Sanshu no Jingi), together with the Sword of Kusanagi and the Yasakani no Magatama (八尺瓊曲玉, Literally meaning: Eight Shaku Curved Jewel).
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.
