Herrera Tresckow

Herrera Tresckohen (トレスコヘン・ヘレラ; Toresukohen Herera) was an arrancar and former member of Aizen's army who secretly plotted to assassinate Aizen. He had a small band of followers, but his plot failed and Herrera fled into the deserts of Hueco Mundo and remained hidden until Aizen's fall. He was the Quinta Espada, though his position, vacated after he fled from Las Noches, was later taken when Nnoitra Jiruga was promoted from Octava, Eighth.

Early years
Herrera was an adjuchas-class Menos prior to shinigamification. He was a member of the the Espada that existed prior to Aizen's arrival in Hueco Mundo, though ranked Quinta, Fifth, by Aizen. Once Aizen arrived and assumed control of Hueco Mundo, Herrera saw the life that he knew fall apart as changes were made. The arrancar hated Aizen and his shinigami allies, especially Aizen himself. Aizen saw the strength that Herrera had and shinigamified him with the Hōgyoku. As with many other arrancars, Herrera failed to defeat Aizen at their first encounter.

Tōsen commented that he did not trust Herrera, to which Aizen replied that he had his uses, given the proper motivation. Herrera was given orders to scout Hueco Mundo in search for Vasto Lordes.

Assassination plot
Under Aizen, Herrera has been plotting to assassinate Aizen out of discontent with his superior. He planned on recruiting Nelliel Tu Odelschwanck and Baraggan Luisenbarn, though his plans were discovered before Herrera could make secret contact with either of them. His underground movement only consisted of Numerós at the time of the discovery. He was the second-to-last member of the original Espada at the time, leaving Aaroniero Arruruerie. His reason for not approaching Aaroniero was said to be because Herrera did not trust Aaroniero or his potential for omnipotence.

Moments before Herrera fled, he fired a Gran Rey Cero from the entrance of Las Noches, causing structural damage and causing a portion of the palace to crumble. The Exequias were about to give chase, but Aizen ordered them to stop, stating that Herrera would not challenge his rule again.

Return to power
Exiled in his own dimension, Herrera struggled to rebuild his resistance as hollows were drawn in by Aizen's promise for greater power. His followers were small in numbers when Aizen finally fell to the shinigami forces, and Herrera used it to his advantage and managed to rapidly expand his own forces. Herrera did not enforce any form of order amongst his men, resulting in tussles and fights as his hollows devoured each other. It limited his manpower, but resulted in an elite force that was feared in Hueco Mundo.

Herrera consolidated his forces and attacked Las Noches, taking over the complex and crowned himself the King of Las Noches.

Personality and traits
Unlike other arrancars, Herrera was moralistic and stubborn about it. He refused to travel to the human world to hunt down spirits to eat and explained himself by saying that they tasted terrible and thus hardly worth the effort. However, Herrera hated how Aizen "just waltzed into [their] den and usurped power like it was no big deal." Being ignorant to the hypnotic powers of Aizen's zanpakutō, Ryūka Suigetsu, Herrera was confident that he could deceive his superior until the very last moment. Herrera expressed his ability to quickly improvise when a plan goes wrong, when he used his Gran Rey Cero within Las Noches to provide a distraction as he made a get-away.

Herrera grew to believe that he could not trust anyone other than himself, cutting himself off from the rest of the world during the time of Aizen's reign. On top of that, Herrerea hated the prospect of being manipulated to do another person's bidding. He was surprised that Aizen did not demote him to the Privaron Espada ranks prior to his escape.

Herrera's lack of social grace was highly evident in his sarcastic attitude. Without any strength to trust others, Herrera's care for others' well-being was limited to his concern for his own safety.

Powers and abilities
Immerse Spiritual Pressure: From centuries of experience, before Aizen appeared, Herrera was able to manifest himself into a deadly force, capable of single-handedly fighting a fifth of Baraggan's enormous hollow army with little effort. Herrera never challenged Baraggan, though, possibly due to the sheer numbers of Baraggan's forces combined with the strength of the King of Las Noches himself. Herrera's strength was comparable to that of Nelliel Tu Odelschwanck during his time in the Espada.

Master Swordsmanship Specialist: Herrera has placed much focus into learning the art of the sword, producing a style of combat that combined both fluid movements and brutal efficiency. Herrera preferred to not take attacks head-on, using momentum of his opponents to take advantage of openings in defenses.

Stealth: Herrera has demonstrated the ability to render himself invisible or camouflage himself to hide from his opponents. Combined with his high degree of control over his reiatsu, Herrera could hide himself from even captain-level shinigami. He, presumably, used this power to great effect in order to remain hidden throughout Aizen's reign.

Cero: As with most arrancars, Herrera has shown the ability to use cero. Herrera has demonstrated the ability to fire powerful ceros without having to charge it up, making the usage of bala almost obselete.
 * Gran Rey Cero: Moments before he made his escape, Herrera defiantly fired a Gran Rey Cero within Las Noches, causing enormous structural damage. He stated that the cero would have obliterated the building if he had the time to charge the cero to cause more devastation, though doubtful that it would have caused anything more than injury to the building's occupants, anyways. Herrera has developed his Gran Rey Cero to the point of being capable of charging two of them at once: one from each palm.

Hierro: Herrera had a strong hierro, being capable of blocking a multitude of shikai-strength sword strikes with his arm, even hooking his arm around the blade to halt its movement.

Pesquisa: Herrera was considered the greatest practitioner of pesquisa in the original Espada. His skills in the technique allowed him to analyze others to the point of telling who the target being interacted with within the past day. He could discern a lot of information about other peoples' spiritual levels and strengths by looking at them. Through pesquisa, Herrera could also perceive slight changes in other people's emotions.
 * Rastro: His skill in pesquisa allowed Herrera to even track down a target after memorizing his target's aura. Herrera called this technique Rastro, Spanish for "trace" or "track."

Zanpakutō
Herrera's zanpakutō, named Comadreja (鎌獣神 (カマレハ); kamareha; Spanish for "Weasel", Japanese for "Sickled God of Beasts"), usually was sheathed at his side, resembling a typical katana. The hilt featured a yellow tassel and the guard consisted of four prongs, with the sharp tips facing the same direction as the blade. It was released by the word Tear (裂く; saku).
 * Resurrección: When Herrera released, his left hand transformed into a long, curved scythe blade. While in resurrección, Herrera wore a mask, similar to what was used for masquerading. Other than these changes, Herrera physically remained similar to while not in resurrección.
 * Resurrección special ability: In this form, Herrera could move quickly enough to make three actions before his opponent could register what happened, even for a seasoned warrior. He was capable of stunning, attacking, and healing within those three actions. Through this, Herrera could cause intense pain in his opponent without leaving any visible indication of a wound.
 * Enhanced Speed and agility: Herrera's impressive agility was further augmented while in resurrección, surpassing that of a captain's flash step.

Behind the scenes
Herrera was designed to go against the evil archetype that is present in arrancars. He is named after Spanish architect Juan de Herrera and German World War II officer Henning von Tresckow, who headed a coup that almost killed Hitler. The character was designed with the intentions to be an antihero.

Herrera did not have a fracción while he was with the Espada.

Superstitions involving weasels say that they are the form taken by witches and banshees, and considered to be the herald of death. It was also considered unlucky to kill a weasel, or to have one cross one's own path. The kamaitachi was a Japanese mythological creature that was said to operate in groups of threes that moved extraordinarily quickly. The first kamaitachi knocked over the victim, the second caused a wound, and the third healed the wound, leaving the victim to suddenly feel excruciating pain without reason.