Absolute Angels are beings created by the grandfather of Kazuya, Kyoshiro, Mika and Sōjirō Ayanokōji(with assistance from Kazuya as well), predecessed by prototype beings known as Steel Angels. Unlike these prototypes, Absolute Angels were developed to as planned, made into the perfect beings they were intended to be. Soldiers that could cause mass destruction on a whim, at the command of a master.
However, things went wrong in their creation, leading to a catastrophe forever known as the Seven Days of Hot Snow.
While the Absolute Angels survived, what had originally been one was split into five, and the world around them was demolished in the wake of the incident.