Aizen Sōsuke 藍染 惣右介 Anime Fighting Free Game

Sōsuke Aizen (藍染 惣右介, Aizen Sōsuke) is the former captain of the 5th Division in the Gotei 13. He later leaves Soul Society with his followers, Gin Ichimaru and Kaname Tōsen. His lieutenant was Momo Hinamori. He formerly served as the lieutenant of the 5th Division under Shinji Hirako. After waging war against Soul Society with an army of Arrancar, Aizen was defeated by Ichigo Kurosaki and sealed away by Kisuke Urahara, and then imprisoned for his crimes.
Prior to his departure from Soul Society, Aizen appeared as a mild-featured man with brown scholarly hair enhanced by square glasses, along with soft brown eyes. He wore the standard Shinigami uniform with a captain's haori.[3] 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 down his face.

In Hueco Mundo, Aizen initially wears Arrancar clothes over his shihakushō.[5] After Orihime Inoue is taken to Las Noches, Aizen wears full clothing similar in style to the Arrancar, complete with a pink sash around the waist.

Upon his 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.