|Height||186 cm (6'1")|
|Weight||74 kg (163 lbs)|
|Previous Affiliation||Arrancar Army, Gotei 13, Soul Society|
|Previous Occupation||Leader of the Arrancar Army|
Captain of the 5th Division
Lieutenant of the 5th Division
Instructor at the Shin'ō Academy
|Previous Team||5th Division|
|Partner||Miharu Nakamura, Toshiko Nagakura, Aoi Hideyoshi|
|Previous Partner||Gin Ichimaru, Kaname Tōsen, Shinji Hirako, Momo Hinamori, Seigen Suzunami (game only)|
|Base of Operations||Las Noches, Hueco Mundo|
|Manga Debut||Volume 9, Chapter 79|
|Anime Debut||Episode 23|
|Video Game Debut||Bleach GC: Tasogare ni Mamieru Shinigami|
|Japanese Voice||Shō Hayami|
|English Voice||Kyle Hebert|
|Spanish Voice||Raúl Llorens (Spain)
Ricardo Mendoza (Latin America)
Sōsuke Aizen (藍染 惣右介, Aizen Sōsuke) is the former captain of the 5th Division in the Gotei 13; he later leaves the Soul Society with his followers, Gin Ichimaru and Kaname Tōsen. His lieutenant was Momo Hinamori. After waging war against Soul Society with an army of Arrancar, Aizen was defeated by Ichigo Kurosaki and then sealed away by Kisuke Urahara.
He later received judgement from the Central 46 and was sentenced to 18,800 years in "Muken", the 8th and lowest level of the underground prison. However, after his time was served, he escaped and returned to Hueco Mundo and started a new project to destroy the Soul Society.
In Hueco Mundo, Aizen is first seen wearing Arrancar clothes over his Shihakushō. Afterwards, after Orihime Inoue is taken to Las Noches, Aizen wore full clothing similar in style to the Arrancar.
Prior to his departure from the Soul Society, he appeared as a mild-featured man with brown scholarly hair enhanced by square glasses. He wore the standard Shinigami uniform with a captain's haori. However, during his ascent to Hueco Mundo, he removed his glasses and swept his hand through his hair, revealing menacing eyes and a very different hairstyle; his hair is now swept back, with a strand hanging in his face. As he had previously revealed to Renji Abarai, the Aizen they all knew never existed and this would seem to be a visual representation of that claim.
Aizen's appearance changes again upon his initial defeat by Ichigo Kurosaki. Aizen loses all of the physical changes made by his transformation and returns to the physical form he had prior to transforming.
Despite his current villainous status and former position of authority, Aizen is a surprisingly polite, soft-spoken intellectual, often addressing his subordinates by their given names. He rarely shows any sign of alarm or distress and often has entire situations planned out well in advance. Whenever confronted, Aizen is casual and uncaring, attempting to draw out a conversation and make small talk, which often infuriates those he is talking to.
Aizen initially appeared to be a very kind, well-respected captain and was looked up to by many, especially his Lieutenant Momo Hinamori. However, this was just a mask to disguise his manipulative and very dangerous nature. In truth, he cares very little for his underlings (both past and present), and is willing to use almost everyone around him as pawns to achieve his means. In his own words, Aizen claims to be unaffected by any form of morals or ethics, as he views them as mere restrictions on his potential. He is, therefore, willing to stop at nothing to further his selfish ambitions, including manipulating or killing anyone if he deems it to be necessary. He is fond of long, complicated, and somewhat convoluted plots, and frequently appears to toy with his underlings for amusement. Unlike most of the other Shinigami who appear to have some kind of honor and kindness, including some Espada, Aizen lacks genuine compassion and honor.
During his time as a captain, he was known to like tofu, but he disliked boiled eggs. In his free time, he often read and he also gave a special lecture of calligraphy at the Shinigami Academy, given that he excelled in this branch of arts. This optional course was immensely popular among the Shinigami students, and many of them felt great sorrow at Aizen's sudden departure.
As the commander of his army of Arrancar, Aizen controls his minions either through acquired respect or fear. Ulquiorra Cifer, one of his noticeably loyal subordinates, revealed in a conversation with Orihime Inoue that they are all there to further Aizen's ambitions. For more rowdy individuals like Grimmjow Jaegerjaquez, he keeps them in line through intimidation and mind games. The Arrancar Aisslinger Wernarr also claims that they follow Aizen because he has no fear, something which beings born from fear and despair find inspiring. Other Arrancar occasionally follow Aizen for reasons unique to themselves, such as Szayelaporro Granz, who follows Aizen with the hopes that he will eradicate the world of all non-Hollows.
To date, the equally manipulative Gin Ichimaru is the only person who seems to be able to see through Aizen's manipulation. Ichimaru has also shown that he has some sense of Aizen's emotions and feelings, correctly identifying that Aizen was enjoying the invasion of Ichigo and his friends and their successes within Las Noches, as well as picking-up on the fact that Aizen had registered the arrival of Hinamori in battle of Fake Karakura Town and was surprised by it. By contrast, Kaname Tōsen has shown no such understanding and has fallen victim to one of Aizen's more minor mind games when Aizen off-handedly manipulated him into punishing Grimmjow for him while Aizen himself kept up his appearance of benevolence.
Aizen's true objective was to overthrow the king of the Soul Society. As he and his fellow traitor captains were departing from the Soul Society, he told Jūshirō Ukitake that "no one has stood on the top of the world", not even the gods, but he aspires to "stand on the heavens and end the unbearable vacancy on the world's throne". To do this, he needs the Ōken (王鍵, Royal Key), a tri-pronged golden key that opens a portal to the dimension in which the Soul King resides. While the location of the key is known only to Captain-Commander Yamamoto, Aizen knows how the original was created and how to manufacture another. To do this, 100,000 souls need to be gathered together (which will kill all the entities used) and vaporize a significant portion of the area used in its forging. His sights are therefore set on Karakura Town, which has an unusually large concentration of spirit particles.
According to Kisuke Urahara, since mastering the Hōgyoku, Aizen has become less cautious in battle, noting that before he subdued the device, Aizen would not have allowed him to use level 90 Kidō, Aizen admits that his new powers allow him to let his guard down. Also due to this newfound power, he has developed more of a seemingly arrogant and overconfident attitude, often not even thinking his attacks or defense through any longer like he used to, or even bothering to find out the effects of his opponents' and his own attacks. In his newest form, he has also developed a severe superiority complex, believing he is now above both Shinigami and Hollows. Because of his superior attitude and high intelligence, Aizen is easily enraged when facing something or someone that he doesn't understand; for example, when witnessing Ichigo in his "Final" form, Aizen becomes furious because he is unable to comprehend how a Human has surpassed him.
At an unknown point in the past, Aizen became part of 5th Division under Captain Shinji Hirako. He invested himself in the research and creation of the Hōgyoku even before Kisuke Urahara. To this end, he sacrificed hundreds of Shinigami and hundreds of Rukongai citizens who bore Shinigami talents to his own Hōgyoku. But it was not satisfied with this. He is seen standing in a clearing with three other Shinigami who are kneeling before him by Gin Ichimaru. One of the Shinigami hands Aizen the Hōgyoku. Aizen puts the object in a glass and then hands it back to the Shinigami. Aizen and his subordinates leave an unconscious Rangiku Matsumoto a short distance away. Aizen eventually caught his captain's attention, and was promoted to a lieutenant in order for Shinji to watch over him closely. However, this Shinji's act only helped the realization of his plans.
110 years ago Aizen was seen making his way to the 5th Division living quarters of his captain. He and Shinji had a discussion about style and trends before they made their way to the promotion ceremony being held at the 1st Division headquarters. As they got there, Aizen witnessed Hiyori Sarugaki attack his captain and the two got into a childish argument. He followed behind while the other captains congregated and had a brief discussion on the status of the Gotei 13. Overhearing Shunsui Kyōraku mention that the previous captain of the 12th Division was promoted, Aizen interrupted and asked what Kyōraku meant by it. Aizen initially conjectured that the promotion was to Central 46. However, Shunsui explained that it had nothing to do with the Central 46 and that the previous Squad captain Hikifune had been accepted into the Zero Division also known as the Royal Guard. Aizen was left surprised at the revelation.
The following night, after Kisuke Urahara's appointment as the new captain of the 12th Division, Shinji had a short talk with him about his new role as captain. While leaving, Shinji asked, "How long do you plan on watching us from over there?" Using his hand, Shinji revealed Aizen concealed behind some form of camouflage. Aizen complimented his captain and asked him when he sensed him there, to which Shinji replied ever since he was in his mother's womb, and ordered Aizen to follow. Aizen noted that won't do at all. Aizen then commented on how scary a person Shinji was, to which Shinji replied that Aizen was the scary one.
The very next night, Aizen saw Gin Ichimaru killing the 3rd seat of their division, and informed him that he was impressed by his skill. Aizen then asked him how he found the fight, to which Gin stated he found it pathetic.
9 years later, Shinji and Aizen were walking around the Seireitei when they came across Urahara, Hiyori and 3rd Seat Mayuri Kurotsuchi. While Shinji once again engaged in a childish fight and argument with Hiyori, Aizen asked Urahara if he had heard the news to which Urahara told him he hadn't. Shinji proceeded to take up the tale and tell Urahara about the series of strange deaths that had taken place in Rukongai. Shinji also informed him that the 9th Division had been sent to handle the investigation.
With the disappearance of the 9th Division, Captain-Commander Yamamoto called an emergency meeting and assembled a team to investigate. After coming into contact with Hollowfied 9th Division members the investigation team was dispatched by an unseen assailant. Aizen was seen wandering around at night by Captain Shunsui Kyōraku and some other Shinigami on guard, while the investigation team was still out searching.
It was later revealed that the 5th seat of the 9th Division, Kaname Tōsen, was behind the betrayal of the 9th Division, having stabbed Kensei Muguruma in the back and killed Heizō Kasaki, Shinobu Eishima and Tōdō Izaemon, who had accompanied Kensei. He subsequently subdued the team sent to locate the missing 9th Division members using his Bankai. When Captain Shinji Hirako of the 5th Division, asked him why he betrayed his captain, he was surprised to be answered by his own lieutenant Aizen, who stated that Tōsen didn't betray anyone and that he is, in fact, very loyal, and he just faithfully followed his orders.
Shinji admits he was not as surprised as he seemed to be, and Aizen asked if he suspected him, stating that he had expected that much from his captain. Shinji then explains how he had known something was dangerous about Aizen and that he couldn't be trusted. It was for those reasons that Shinji chose him to be his lieutenant, so that he could keep an eye on him. Aizen told him that he was grateful, as due to his deep seated doubts he didn't suspect a thing. When Shinji states that he already made it known that he had suspected him, Aizen elaborated stating that he didn't realize that for the whole past month, it wasn't him walking behind him. Aizen proceeded to explain the power of his Zanpakutō, Kyōka Suigetsu. Aizen informs Shinji that if he was as close to Aizen as other captains were to their lieutenants he would have been able to see through it by picking up on subtle differences between Aizen himself and Aizen's double. It was his lack of trust that kept them from getting close and as such, allowed Aizen to fool Shinji. He also explains that he could have always refused to be Shinji's lieutenant but decided against that action because his captain's skepticism made the position ideal to carry out his plans. Aizen thus laid the blame for Shinji and his comrades' current predicament at the feet of Shinji. Provoked by this, Shinji's anger triggered a speed-up in the Hollowfication process. Aizen thanked him for being so easily provoked and made a note of the observed connection between Hollowfication and agitated emotions.
As he got ready to kill Shinji and the others, Kisuke Urahara and Tessai Tsukabishi arrived to stop Aizen from dispatching his captain. Aizen and Urahara had a brief discussion about what was transpiring, with Aizen acting innocent at first until Urahara notes that the investigation team doesn't have simple injuries, but were in fact going through Hollowfication. Aizen commended Urahara on his deduction and revealed himself to be behind the disappearances in the Rukongai. As Aizen had been engaging in early experiments on Shinigami/Hollow hybrids, which involved using an unknown device to cause spirits to transform into Hollows, he was responsible for turning his former captain and seven other Shinigami into Visored, though Aizen refused to go into any of those details.
Aizen proceeded to leave the scene of the crime with his henchmen, stating that "there's nothing more to do there". To stop them from retreating, Tessai performed the Hadō #88, "Hiryugekizokushintenraiho" spell against them, only to be countered by Aizen using Bakudō #81. "Dankū", allowing them to escape.
Some point after the Hollowfication incident, Aizen became Captain of the 5th Division, and eventually revealed to Gin the secret to avoiding Kyōka Suigetsu's complete hypnosis. He later made Gin his lieutenant. Aizen continued to experiment on Hollows to transform them into Shinigami and he created Hollows that were close to Shinigami, such as Metastacia and Menos Hollows capable of concealing their reiatsu. While testing out the mentioned breed of Menos, he and Gin saved the then first year academy students Momo Hinamori, Izuru Kira, and Renji Abarai from them. Aizen's interest was then piqued by them. Realizing their potential, Aizen took them all into his division. While the obedient and loyal Kira and Hinamori became the lieutenants of the 3rd and 5th Divisions under Gin and Aizen, respectively, Renji proved to be too rebellious and was transferred to the 11th Division (later transferring to the 6th to become that squad's lieutenant).
Gin and Tōsen later became captains of the 3rd and 9th Divisions, respectively, but remained loyal only to Aizen. According to Aizen, even when Hinamori was his lieutenant, he always thought of Gin as his subordinate.
At some point during their captaincy, Aizen, Gin and Tōsen, secretly visited Baraggan Louisenbairn, King of Hueco Mundo and Lord of Las Noches. He and Baraggan engaged in a light conversation and he asked Baraggan to look at his Zanpakutō, he then asked Baraggan if he was happy in his position and if he would join him in a new world where he will be granted more power. Baraggan dismissed this notion stating that there was no power higher than his. Aizen then released his Shikai and showed Baraggan the decimation of his army and subjugating him in turn. Baraggan promised to seek Aizen's destruction for all eternity.
Aizen became aware of the existence of Ichigo Kurosaki when he was born. Understanding the significance of his birth, he had decided to aid his development for his plans. To this end, he had Rukia Kuchiki stationed in Karakura Town. He also put into place obstacles that would force Ichigo to grow stronger, including the Hollow that attacked his family and the Menos Grande that appeared when Uryū Ishida used the Hollow bait.