Blaze Release: Kagutsuchi is a technique which applies shape transformation to the black flames of Amaterasu, allowing the user to manipulate them at will. In Sasuke's case, while Amaterasu is cast from his left eye, he uses his right eye to manipulate the flames. After Sasuke's Susanoo enters its armoured form, it gains an orb of black flames, which serves as an alternate source of flames to manipulate with this technique.
The user can shape the flames in different varieties, for both offence and defence.
- While using the ribcage state of Susanoo, the user can create a defensive encampment by manipulating the flames to cover it.
- Converging the flames in front of the user, a barrier of spike-shaped flames can be created that not only shields him, but also pierces and burns any opponent that touches it.
- Among the weapons that can be manifested from the orb of black flames wielded by Susanoo are swords, magatama-shaped projectiles, and arrows that can be fired from its bow.
- The flames can be wielded in the user's own hand without being incinerated, and can be manipulated into a flexible sword, as well as launch spike-shaped projectiles from the blade for a long-ranged attack.
- The black flames can be used simultaneously with the Chidori to enhance the latter's destructive power.
Similar to other Mangekyō Sharingan abilities, Kagutsuchi's name is derived from Japanese myth and religion. Kagutsuchi is the God of Fire in Shinto and the one who brought death into the world by burning his mother Izanami to death as she gave birth to him. This made his father, Izanagi, kill him with the Totsuka sword.
- In chapter 415, Sasuke puts out the flames of Amaterasu with his right eye. It's unknown if this is part of Blaze Release: Kagutsuchi, since the fourth databook states that Sasuke invented the technique when he fought A.
- Although the sword version utilised by Susanoo was initially identified as "Blaze Release: Kagutsuchi" in the manga, it was later named as part of a derivative technique called "Blaze Release: Susanoo Kagutsuchi". And in Naruto Shippūden: Ultimate Ninja Storm 3, it is named "Sword of Kagutsuchi" (加具土命の剣, Kagutsuchi no Tsurugi, Literally meaning: Added Tool Earth-Lord Sword).
- In chapter 585, the furigana of this technique's name were written in hiragana, not in katakana, as they're usually written.