Futsunushi (Ash)

Futsunushi (経津主, Haven-Passing Lord) is the first of Kogo Uchiha's two, unique Mangekyō Sharingan techniques. This technique was initially manifested in his left eye, but due to its destruction, was subsequently awakened in his right eye along with Hiruko. Futsunushi is a technique that is thought to be derived from the famous Amaterasu technique; the basis of this theory can be seen from mythology. Futsunushi is an extremely powerful Genjutsu technique that is able to interact with inanimate objects - the extent of its power. It utilizes the Mangekyō Sharingan in order to cast an illusion upon the shadow of anything within Kogo's radius, whether it be inanimate or animate. This is achieved through the theory that everything in the universe has chakra, no matter how inanimate. By way of this, Kogo disturbs the chakra flow within the shadow - in a similar vein to the Nara Clan's Hiden techniques - and provides him with the capability to draw it to himself, detaching themselves from their owners.

Once this has occurred, the technique subsequently allows Kogo to utilize the concentrated shadows as a means to supplement the power of a variety of different techniques. He can use them in conjunction with his shadow-based illusions in order to actually conjure their effects; more commonly he will use them with his Fire Release. True to the namesake of the technique, when his Fire Release techniques are empowered with shadows, they are enhanced to the point where they can, temporarily, fight against techniques of Amaterasu's calibre. Strangely, after absorbing the shadows, the flames of Kogo turn to become a very vibrant yellow, and possess a much higher level of speed and impact, thereby making them reminiscent to lightning to some extent. It should be noted that Futsunushi cannot be used to enhance any Kekkei Genkai. However, because of the properties of Futsunushi, should the shadow come in contact with an opponent's techniques, Kogo may possess them as his own and utilize them with much higher power against his enemies. Albeit, the usage of such a method drains his chakra reserves much more readily.

Previously, the power of the technique was much higher. When manifested in his left eye for the first time, Kogo was capable of manipulating these shadows into a physical form, allowing them to quite easily be used as piercing blades, large waves, shields, and varying other constructs. Furthermore, Kogo could subsequently use his right eye as a means to shroud himself with these shadows, providing him with an almost impervious robe of damage, mainly because all techniques that attempted to make contact with him were consumed by the shadows. Nonetheless, the technique still holds tremendous potential, and it is assumed that because of the limitations behind its current use, Kogo understands how to use it with much more precision currently.

Trivia

 * Futsunushi (経津主, Haven-Passing Lord) is a Shintō kami of Fire and Lightning, and is a general of Amaterasu. This technique parallels that based on Kogo's usage with the consuming of the Fire Release nature, thereby giving it lightning-like speeds and brightness.
 * The initial "Genjutsu" cast upon the shadows is possible due to the influx of into the shadows by way of Kogo's activation of the Mangekyō Sharingan.