This article is under construction. Please excuse the mess.
The Rapid Evening is a galactic intercessory group with access to highly advanced technology. It appears to have at least fifty thousand--if not more--years of continuity. They are the active arm of the Principality of Kesh.
The machine which directs the Rapid Evening from the planet of Kesh (created in the period between COUNTER/Weight and Twilight Mirage) is referred to as Crystal Palace.
Structure
Some agents appear to act on their own as spies and/or saboteurs, reporting information to higher-ups and acting as necessary (such as Jamil or Natalya). Squad formations include planetary assault squads, like the one led by Kiva Helsing, or the Heresy Squads designed to target Divines, like the one led by Tetsuya Mori in COUNTER/Weight.
The existence of the Mirage Division suggests that agents and squads are broadly grouped into divisions that work in specific areas, though it's unclear if this was true before the Rapid Evening began to expand its remit outside the Golden Branch. Primary-Satellite pairs like Demani and Gray allow them to survey long-term areas of interest like the Twilight Mirage.