When Halibel was a Vasto Lorde long ago, she recruited Emilou Apacci, Franceska Mila Rose and Cyan Sung-Sun to be the Tres Bestias, tasked to grow stronger and to kill ravenous hollows. The quartet later encountered Baraggan when he was king of Hueco Mundo, who offered her to join his side, but she declined, also wounding a shark-like hollow who approached her. After Aizen, Gin and Tōsen arrived in Hueco Mundo to recruit Baraggan, Aizen also took an interest in Halibel. Some time later, Halibel is attacked by the shark-like hollow, which has now turned into an arrancar. Although the Tres Bestias tried to help her, they are eventually defeated. Just when the shark-like arrancar is about to kill Halibel, Aizen suddenly appeared and killed the arrancar, then offering Halibel a place in his arrancar army and telling her that no one would have to be sacrificed in order to grow stronger. In the present, Halibel angrily attacks Aizen, but she is then stabbed in the back of her left shoulder by Aizen, who used an illusion to deceive her, sending her plummeting into the city below. Aizen then challenges the Soul Reapers and Vizards in combat.