Hierro

is a defensive Arrancar technique.

Description
The user's Reiryoku condenses, creating a steel-hard skin strong enough to block a Zanpakutō. This allows users to confront some of the sword-wielding Shinigami barehanded. While this technique is exhibited by all Arrancar to some degree, the strength of an individual's Hierro is entirely proportional to the potency of their Reiryoku, with Nnoitra Gilga possessing the self-proclaimed strongest Hierro out of all generations of the Espada. However, it is unknown if such claims were true, given that Nnoitra was outranked by five Espada of higher power and a former third Espada injured him without complication. Although Hierro can defend against the attacks of a released Zanpakutō, 11th Division Captain Kenpachi Zaraki discovered he could cut Nnoitra's body in spite of it by adapting to the latter's Reiatsu.

Trivia

 * In the English dub of the Bleach anime, Hierro was mistakenly identified as Cero when Ulquiorra Cifer spoke about Ichigo being able to effortlessly cut off Yammy Llargo's arm.