Sōsuke Aizen
After saving Rangiku, Gin secretly swore revenge on Aizen. His unsettling appearance, apparent ruthlessness in battle, and apparent betrayal of the Soul Society were necessary to facilitate this. The first step in his revenge was joining one of the 13 Guardian Divisions. Gin was considered a child prodigy since he graduated from the academy within a year and was assigned to a seated position in the 5th Division. Killing the 3rd seat of the division with ease, Gin aroused Aizen's interest in him. He swore his loyalty to Aizen from the day they met, though only so he could discover Aizen's weakness and avenge Rangiku's near death when the time came. Eventually Gin became lieutenant of 5th Division under Captain Sōsuke Aizen. As captain he was in command of 3rd Division.