Holly

{{original}} In the Bleach universe, a hollow is a monstrous soul-eating spirit that results when a deceased soul is consumed by negative emotions or is forcibly converted by other hollows. All hollows have masks attached to their faces and a hollow hole somewhere on their bodies; they also have a tendency to attack those who were close to them in their human lives, which they superficially have no recollection of. Hollows possess individual reishi and intensify it through devouring any soul they come across. The 2018 film elaborates that the hollows had played a role in the concepts of the mythological creatures like Yokai.

{{original}} An arrancar is a hollow which has gained Soul Reaper-like characteristics through the removal of its mask, thus resulting in an increased combat versatility and more humanoid appearance. The transformation of a hollow into an arrancar can occur either naturally or artificially, but there is little information on process that occurs. The arrancar affiliated with Aizen wear distinctive white uniforms. They retain the Mexican aesthetic borne by hollows, and according to Tite Kubo, many of them are named after real life architects and designers. The arrancars (except the ten Espadas) are given individual numbers which are based on the order of their birth (starting at the number 11); most arrancars are labeled as part of the Números (数字持ちヌメロス, Numerosu, Spanish for "Numbers", Japanese translates as "Number Holders").

{{original}} Soul Reapers, including protagonist Ichigo Kurosaki, have two primary duties: Purify any hollows they encounter to protect other souls from being devoured, and perform the soul burial (魂葬こんそう, konsō) ritual to lay ghosts to rest before they become hollows. When either of these duties is fulfilled, the soul goes to the Soul Society to live as an ordinary human until eventually reincarnated back to earth. But a hollow who committed grave sins in life is dragged into Hell for punishment.Hollow intrusions into Ichigo's hometown are the driving plot force for Bleach's first arc, at the end of which Ichigo leaves earth for Soul Society in order to rescue one of her friends.

{{original}} Arrancar are introduced into Bleach following Ichigo's return from Soul Society, serving as major antagonists until their collective defeat in the Fake Karakura Arc. Most of the arrancar antagonists served Sōsuke Aizen, who used an item called the hōgyoku to artificially create more arrancar. While more conscious than their original hollow selves, some arrancars are either sadistic psychopaths or display honor or compassion which resulted in some befriending the heroes. The arrancar are first shown scouting Ichigo's hometown by ones and twos, which escalates into sorties, and eventually a battle on earth and in Hueco Mundo between the most powerful arrancar and Soul Reapers. Following Aizen's defeat, the arrancar survivors attempted to become their society before they conquered by the Quincy extremists known as the Wandenreich, with those captured either drafted as expandable foot soldiers or executed as monsters.

{{original}} The Hollows and arrancar inhabit a dimension called Hueco Mundo (虚圏ウェコムンド, Weko Mundo, Spanish for "Hollow World," kanji translates as "Hollow Domain"), a vast barren desert with quartz "trees" which any hollow can access, leave and return to by tearing a hole in space called a Garganta. While in Hueco Mundo, most hollows can sate their hunger simply by breathing the reishi-rich air, and are threatened only by other hollows who have turned to cannibalism, conquest for power and sport, or both. Hueco Mundo is initially portrayed as impossible to access by non-hollows, but techniques for traveling there are eventually revealed, and Hueco Mundo was entered by outsiders, first by protagonist Ichigo Kurosaki and her allies, then later by Quincy conquerors. An enormous white domed palace called Las Noches (虚夜宮ラス・ノーチェス, Rasu Nōchesu, Spanish for "The Nights," kanji translates as "Hollow Night Palace") in Hueco Mundo, initially ruins, was used by Aizen to garrison his troops.