GENERAL
Hueco Mundo (虚圏 (ウェコムンド), Wekomundo; Spanish for "Hollow World", Japanese for "Hollow Sphere") is the dimension in which Hollow and Arrancar usually reside. It lies in between the Human World and Soul Society.
Overview
An unchanging night covers the sky, an endless white desert covers the ground. The tree-like objects are not plants, but rather quartz-like minerals.
Hueco Mundo as it originally appeared, with a black and white sky. It was a different area, where Grand Fisher apparently frequented.
The landscape of Hueco Mundo is a seemingly never-ending white desert, with a multitude of dunes, littered with boulders. In Hueco Mundo, the moon is on the opposite lunar phase of that in the Human World. The vast desert seems to lack any bodies of water and contains rocky formations. Like in Soul Society, the atmosphere is filled with a high concentration of Reishi, thus allowing smaller Hollows to gain nourishment despite the lack of Human souls.
Similar to the case of real world deserts, active life in Hueco Mundo appears to be few and far between. Hollows generally dwell below the surface or in other areas until something provokes them to leave their shelter, like the intrusion of a foreign entity. According to the Shinigami, all Hollows dwell in Hueco Mundo regardless of their shape, size, or power.
Accessing Hueco Mundo
Hueco Mundo is located between the Human World and Soul Society, though it is separated from the bordering dimension known as the Dangai. It can only be accessed via Garganta, which tears the dimensional fabric separating the worlds, allowing Hollows to travel to any other dimension at will.
GOVERNMENT
Hueco Mundo has no formal government. In Hueco Mundo, the strongest being wields power. If there is no particular leader or organization, Hueco Mundo runs as usual.
MILITARY
Espada: Ten of the most powerful Arrancar. Ranked 0 through 9 based on their combat ability. Their ranks are tattooed on their bodies.
Fracción: Arrancar who serve under the Espada. The Espada are allowed to have as many Fracción as they want.
Privaron Espada: Arrancar stripped of their Espada rank and given a Tres Cifras rank.
Exequias: A unit responsible for eliminating intruders in Las Noches. They recovered battle records from Arrancar who were defeated by Ichigo Kurosaki.
LOCATIONS
Las Noches: A series of buildings surrounded by a large dome. Formerly ruled by Baraggan Louisenbairn, King of Hueco Mundo, it became the headquarters of Sōsuke Aizen and his army of Arrancar for a short time.
Forest of Menos: There exists a vast forest underneath Hueco Mundo where Menos-class Hollows reside. The trees in this forest extend to the surface and dot the landscape above ground. The Adjuchas-class Menos which reside in this forest are under the control of Aizen.
Negal Ruins: During the Quincy Blood War, Kisuke Urahara sets up his temporary base of operations here.
