Sosuke Aizen

Lore & Background

Aizen spent his life working within the Fifth Division, eventually becoming its lieutenant under Shinji Hirako before rising to captain. He gained followers including Gin Ichimaru and Kaname Tōsen. A century prior to the series, after Kisuke Urahara created the Hōgyoku, Aizen began experimenting on Soul Reapers who would become Vizards, using Shinji's mistrust against him. He framed Urahara for these experiments, forcing his exile, and learned that the Hōgyoku grants desires to those with sufficient will.

Aizen took Shuhei Hisagi, Momo Hinamori, Izuru Kira, and Renji Abarai into his division. He created Metastacia and White, playing roles in events concerning Rukia Kuchiki, Isshin Shiba, and Masaki Kurosaki. After fleeing to Hueco Mundo with Ichimaru and Tōsen, he killed Barragan's minions during a discussion to force the former Arrancar king into servitude. There, Aizen reconstructed Las Noches in his image and recruited Tier Halibel and other Arrancars as his Espadas.

Reader's Guide

Sousuke Aizen is an extremely powerful combatant well above many captain-level Soul Reapers. He noted that the half-awakened Hōgyoku could be fully activated temporarily by fusing with someone having at least twice the spirit pressure of an average captain. After embedding the Hōgyoku into his body, he underwent transformations granting extraordinary power boosts. Originally wielding the zanpakutō Kyōka Suigetsu, its Shikai ability Kanzen Saimin (Complete Hypnosis) activates with the command "shatter" and affects anyone who watches the sequence once.

Escape is possible only by touching the blade before activation, as Gin overheard, or by reading the blade's force like Yamamoto did. After his final evolution, Aizen became immortal. His powers were sealed only by Ichigo's Mugetsu technique. In this state, Kyōka Suigetsu dissolved, with its powers becoming part of his being.

Key countermeasures included Gin overhearing the activation condition and Yamamoto grabbing the blade to distinguish Aizen from illusions.

Did You Know?

• Gin Ichimaru overheard Aizen's command "shatter" before Kyoka Suigetsu was activated, allowing him to touch the blade and escape the illusion later.
• After his final evolution, Aizen no longer needed the physical sword Kyoka Suigetsu as it dissolved with its powers becoming part of his being.
• In 2021, Tite Kubo drew an illustration of Aizen in a pose similar to Loki from the TV series to emphasize their shared traitorous and conniving personalities.

Rise from Shadows

Aizen served as lieutenant under Shinji Hirako before becoming captain of the Fifth Division, gaining followers like Gin Ichimaru and Kaname Tōsen. A century before the series, he experimented on Soul Reapers using the Hōgyoku to create hybrids, manipulating Shinji by exploiting his mistrust. He framed Kisuke Urahara for these experiments, forcing Urahara's exile while learning that the Hōgyoku grants desires to those with the will to use it. Aizen recruited Shuhei Hisagi, Momo Hinamori, Izuru Kira, and Renji Abarai into his division.

He created Metastacia and White, playing a role in events involving Rukia Kuchiki, Isshin Shiba, and Masaki Kurosaki. After leaving the Soul Society with Ichimaru and Tōsen, he traveled to Hueco Mundo. There, he killed Barragan Luisenbarn's minions to force Barragan into servitude, appropriated Las Noches, and recruited Tier Halibel and other Arrancars as his Espadas.

Grand Design and Betrayal

Aizen arranged for Rukia Kuchiki to meet Ichigo Kurosaki so he could become a Soul Reaper. He sent Hollows to Karakura Town to alert the Soul Society about the Hōgyoku concealed in Rukia's body, secretly killed members of Central 46 Chambers, and used his Zanpakutō to create illusions of them sentencing Rukia to death. Gin faked Aizen's death while Squad 4 Captain Retsu Unohana uncovered the truth as Aizen removed the Hōgyoku from Rukia before escaping to Hueco Mundo with Gin and Tōsen.

His goal was to sacrifice Karakura Town's souls to create an Ōken and kill the Soul King. He strengthened Arrancars using the Hōgyoku, sent Espadas to the Land of the Living for information on Ichigo, and kidnapped Orihime Inoue under the pretense she could save the deteriorating Hōgyoku. This kidnapping was a distraction to cut the Soul Society's forces in half before attacking Karakura Town. After defeating Stark and Barragan, Aizen struck down Halibel to fight personally.

He revealed his role in Ichigo's life when confronted by him, noting Ichigo was unaffected by his Zanpakutō. He nearly revealed Ichigo's lineage before Isshin intervened.

The Fall of a God

Aizen traveled to the Soul Society to create the Ōken but intended to kill Ichigo's school friends first. Gin wounded Aizen, revealing he had pretended to be his right-hand man until the ideal moment to betray him. The Hōgyoku answered Aizen's will to survive, evolving him into another form that mortally wounded Gin before Ichigo arrived. Despite expecting no threat due to a lack of spirit energy, Aizen was overwhelmed by Ichigo's enhanced physical strength.

Fear caused the Hōgyoku to turn Aizen into a Hollow-like monster, but he barely survived Ichigo's final attack, evolving once more to become immortal. However, Ichigo's attack weakened him enough that the Hōgyoku no longer acknowledged him; he reverted to human form and was engulfed in a specially made kidō "Seal" planted by Urahara. Ten days later, after numerous seals rendered him immobile, Central 46 sentenced him to 18,800 years in the 8th prison, "Muken."

His arrogance led to him being gagged and his sentence escalated to 20,000 years. During the Wandenreich invasion, Aizen refused Yhwach's offer to join but delayed them sufficiently before retreating. In the second invasion, Head-Captain Shunsui Kyōraku unsealed Aizen's gag; this allowed Aizen to remove all seals except the last two. Freed, he accompanied Shunsui to the Seireitei, destroyed shadowy creatures produced by Yhwach, and created a path to the Soul King's Palace.

He used his illusion to give Ichigo an opening to fatally wound Yhwach before returning to his cell. Ten years later, Aizen sensed Yhwach's Reiatsu had disappeared, remarking that Yhwach's desired world would be without hope and contrasting it with courageous individuals like Ichigo.