He usually covers his face with an elongated white mask covered with eight holes while in the light. In place of a normal head, he has a large, glass cylindrical capsule filled with red liquid and two small, floating Hollow heads. The two heads are both tattooed with the number 9 and tend to talk in tandem when revealed, giving the effect of two people speaking in turn. The upper head speaks with a deep voice while the other speaks in a high-pitched, child-like voice, and appears to have a level of individuality. His outfit like most Espada is customized; he wears a dress garb that covers his entire body as opposed to the normal jacket and hakama. He also wears a frilly nobles' coat that acts as his replacement jacket and a single white gentleman's glove. The remains of his Hollow mask fragments are on both of his heads, the upper head having 3/4's of his head covered with the mask, and the lower head covering only half of it. After his resurrection by Diosa, he begins donning Kaien's appearance as often as possible.
Aaroniero expresses some amount of pride in his ability to "continue evolving" and his position as an Espada, despite his Gillian status. Somewhat cruel, cold-hearted and sadistic, Aaroniero enjoys toying with his opponents, particularly those he has information on from his absorbed memories, asking Rukia to kill her comrades to make up for Kaien's death. Interestingly, his two heads have a degree of individuality, since they refer to themselves in plural when exposed, and each reacted differently to the idea of death (the bottom head panicked and screamed for Aizen's aid while the top one merely cursed Rukia).
Expert Swordsman Specialist: By absorbing Kaien Shiba (albeit indirectly), Aaroniero was a highly skilled swordsman fighting Rukia based on Kaien's memories. He uses Kaien's techniques and form during the battle, and are described by Rukia as "His upper-body stance. Spear technique reminiscent of a dance, using one wrist as the center of its rotation. Then crushing the opponent between the spear's thrust and the rising waves".
Great Spiritual Power: Having absorbed thousands of Hollows and indirectly absorbing the fairly powerful Soul Reaper Kaien Shiba, Aaroniero has accumulated a rather large amount of spiritual energy. He has enough spiritual power to mimic the levels possessed by Kaien Shiba, going as far as being able to use Kaien's Zanpakuto with presumably the exact amount of spiritual energy required to wield and use its abilities.
Glotoneria (Eating Hollow): Aaroniero's Zanpakuto takes the form of a deformed, brown-tentacled appendage with a gaping maw at the center, surrounded by various tentacles. He commonly hides it under the glove on his left hand.
- Resurrección: It is activated by the command Devour. When released, it turns Aaroniero's lower body into a huge, purple blob-like mass resembling an incredibly bloated invertebrate, with dozens of stubby tentacles and large mouths complete with teeth.
Resurreccion Special Ability