Space dust. Name given to all the harmful and unpredictable particles generated from the planet that lost its function. Although it is harmful to humans, sometimes it gives an unique effect to their body, and some call it Ether.
The Hundred A-rays, Human Species, Knights, are all new species created by this Gin. The energy transfer rate of the Gin scattered in atmosphere is incredible, and it resulted in a new level of warfare that was never possible on this planet.
With A-rays who can take in Gin into their body and Demonic Swords crystallized by Gin, all the weapons of the old age became useless.

Angel Voice: Notes.