Sōsuke Aizen
Squad Nine was originally led by Kensei Muguruma until he and his lieutenant Mashiro Kuna were forced to forfeit their posts after Sōsuke Aizen placed them through Hollowification. Kaname Tōsen, Aizen's accomplice, takes Kensei's position until Aizen revealed his true colors. After Shūhei briefly takes over captain duties for a while, he becomes a co-lieutenant when Kensei and Mashiro resume their duties after Aizen was defeated.