In the perpetual night and white sand world of Hueco Mundo, Ichigo and the others fight their way to Las Noches, the stronghold of former Soul Reaper captain Sosuke Aizen, where Orihime is being held. In the depths of Las Noches, Rukia encounters Espada Number Nine, Aaroniero Arruruerie, who removes his mask to reveal a very familiar face-could he really be former Squad Three Lieutenant Kaien Shiba?