Sosuke Aizen

Sōsuke Aizen
Bleach character
Sōsuke Aizen by Tite Kubo
First appearance	Bleach manga chapter 79 Bleach anime episode 23
Created by	Tite Kubo
Voiced by	Japanese Shō Hayami English Kyle Hebert
Profile
Species	Soul Reaper

Sōsuke Aizen (藍染 惣右介, Aizen Sōsuke^?) is a fictional character and the main antagonist for most of the first half of the manga series Bleach (and the most significant antagonist for the entirety of the anime adaptation) created by Tite Kubo. He is the captain of the 5th Division when he is first introduced, but later betrays the Soul Society and becomes the series' main antagonist until he is defeated by Ichigo Kurosaki and sealed by Kisuke Urahara. His former lieutenant is Momo Hinamori.

Aizen spent much of his career in the 5th Division, eventually becoming its lieutenant under the former captain, Shinji Hirako. Aizen also gained followers in Gin Ichimaru and Kaname Tōsen. A century before the series' setting, after Kisuke Urahara created the Hōgyoku, an item that he believed creates Soul Reaper/Hollow hybrids, Aizen began to experiment using the Soul Reapers that became the Vizards. Among his test subjects was Shinji, who knew Aizen was up to no good but learned too late that Aizen used his distrust against him. Having also framed Kisuke for the Vizards' creation and forced his exile, Aizen learned the Hōgyoku actually grants its user's desires if they have the will to carry it out. But as Kisuke took the Hōgyoku with him, Aizen bides his time to take the item when the time comes.