aroniero Arruruerie

One of the members of Aizen Sousuke's Arrancar organization, the Espada.

Among the Espada, he is the only one originating from the Gillian class (the lowest rank), and according to the 7th Espada, Zommari Rureaux, he is also one of the survivors of the first generation "Espada" that Aizen initially created.

Therefore, he is considered one of the oldest members among the Espada and is thought to be quite an ancient Hollow. Additionally, like Ulquiorra Cifer and Zommari, he does not have any subordinates.

He usually covers his entire head with a vertically long mask with four peep holes and wears a Shihakushou with a frilled collar.

Initially, he was the only Espada whose true face was not visible, and he exuded a rather eerie presence, with bubbling sounds occasionally heard from beneath his mask and his speech sometimes shifting to a katakana accent.

His true identity is Shiba Kaien, the former lieutenant of the 13th Division of the Gotei 13, who was thought to be dead. He disguised himself as an Espada to defeat Aizen, using the alias "Aaroniero" to operate in the shadows. According to him, all places exposed to the sunlight in Las Noches are under Aizen's surveillance, which is why he avoids going out under the sun.

In the story, he comes into contact with Rukia Kuchiki, who once admired Kaien, leading to an emotional reunion... or so it seems?