Black Ash (霊骸, rei mukuro) otherwise known as Elemental Bones is the conversion of corpses of Elementals. It is a lethal soot-like powder that is poisonous to the majority of the living species, including Imanity.
Black Ash is primarily created with the use and consumption of magic. Black Ash storms were a common occurrence during the war, and would often slowly destroy buildings or structures over time.
Although it is named Black Ash it is known to shine an aquamarine light this is due to the fact that the nature of it is a symbol of death itself.
Those that are immune to the Black Ash can still be severely damaged or killed if they consume a living species that are severely harmed with the Ash. This is shown in the No Game No Life: Zero movie when a Ghost is able to negotiate with a Werebeast by having exposed himself to Ash. The Werebeast became disgusted, and allowed him to speak, later taking the advice and destroying the Dwarf Development Facility.
During the Great War, humans would wear dust masks and fur coatings in order to prevent themselves from coming into contact and inhaling Black ash. Black ash was also used by some of Imanity to conceal their identities by applying it directly onto their bodies in order to disrupt identification magic and the senses of the other races.
Black Ash can cause extreme effects on flesh tissue. Schwi, an Ex-Machina, states that she has specific decontaminants to keep herself from deteriorating while in contact with Black Ash. This requires every single part of the human body to be covered with clothing, gloves, goggles and more. For Imanity, if Black Ash touches any part of their bare flesh, whether inside or out, it can cause the following:
- Burnt skin
- If consumed, the innards will be dissolved.
- Complete loss of limb
- Severe lung damage, often leading to death
- Bone fragility
- Severe brain damage, often leading to death
- Destroy or mask any or all connection to elementals and the Spirit Circuit