anime and manga feature an extensive cast of beings known as Hollows
(虚 (ホロウ), Horō
?), the central antagonists of the series. These are malevolent, deceased souls of formerly ordinary humans in the Bleach
universe. Much of the series focuses on the Arrancars (破面 (アランカル), Arankaru
?), more powerful variants of Hollows. The Arrancars make up the army of Sōsuke Aizen, the primary antagonist, and have a system of ranking based on strength. The most prominent Arrancars in the series are the ten most powerful Espadas (十刃 (エスパーダ), Esupāda
?) and their direct subordinates.
The creator of the series, Tite Kubo, uses many Spanish motifs for Hollows. This is most prominent in the names for the various Hollow and Arrancar attack techniques. Many of the Arrancars also have Spanish-derived names.
A Hollow is a spirit that becomes an evil incarnation of itself. When the soul loses its Chain of Fate (因果の鎖, Inga no Kusari
?), the link to its physical body, it then transforms into a skeletal monster. It is possible for a soul to avoid turning into a Hollow and instead become a Visored by awakening its dormant Soul Reaper abilities, as happens to the protagonist, Ichigo Kurosaki.
One plane of existence in the Bleach
universe is the desert-like realm of Hueco Mundo (虚圏 (ウェコムンド), Weko Mundo
?, Spanish for "Hollow World," Japanese for "Hollow Range") where the Hollows thrive on a life force, "spirit energy." The Hollows that appear in the human world have a strong desire to feed on human souls in an attempt to fill the void left in their hearts from losing their Chains of Fate, which is why they are said to first attack the people that they had loved the most in their past lives. Hollows generally do not have recollections of their lives as humans. Hollows have varied character designs, though most are designed with monster-like appearances, skull-like masks and a large hole somewhere through each of their bodies.
There are two main duties of the Soul Reapers regarding souls: to perform a ritual known as a soul burial (魂葬 (こんそう), "konsō"
?) on normal souls before they become Hollows, and to purify the sins of Hollows so they once again become normal. When either of these duties are fulfilled, the soul goes to the Soul Society. If a Hollow committed grave sins as a human, its destruction opens the gates of the underworld, where it is dragged to its punishment.