Ninth Espada Arroniro Arleri
Much later, Rukia encounters the ninth Espada, Arroniro Arleri (アーロニーロ・アルルエリ, Āronīro Arurueri?), while in Hueco Mundo. He leads her to a dark room since Aizen can see everything in the "sunlight" of Las Noches. He then removes his mask, revealing Kaien Shiba's face. He explains that Kaien is responsible for his appearance. The hollow that merged with Kaien was built in a such a way that it would return to Hueco Mundo when destroyed. Having been merged with Kaien at the time of its death, the two were sent back as one merged entity
. In addition to having Kaien's appearance, Arroniro also possesses Kaien's memories and zanpakutō.
While the other arrancar believe the hollow is the one in control, Arroniro asserts that it is actually Kaien who is dominant.
However, Arroniro's behavior is extremely erratic: he claims to be Rukia's friend and then strikes her, suggests that Rukia kill her friends in order to earn his forgiveness, and alternates between being serious and joking almost instantly.