Aizen and the Genius Boy

Summary
Urahara takes Hiyori to the Maggots Nest, explaining on the way that its purpose is to hold people deemed potentially dangerous by the Soul Society. Because it is underground and heavily guarded, the prisoners are free to walk around, doing as they please. While they are walking through the penitentiary, a large prisoner attacks Hiyori, who accidentally left her zanpakuto back at their division headquarters. Urahara easily subdues the man with his bare hand, stating that using one's hands is the only way to thwart an attack in the prison. Deep inside, a younger Mayuri Kurotsuchi; confined to his own cell, is approached by Kisuke in regards to being his second in command in a new division of their own making, the Technological Research Bureau. Mayuri is reluctant, but eventually gives in and agrees. Elsewhere, a young Byakuya Kuchiki is shown to have been easily irritated at that age, proven when Yoruichi demonstrates her flash step technique, stealing his hairpiece before escaping, taunting him in the process. Kaien Shiba is also offered the position of lieutenant under Jushirou Ukitake, but he stubbornly refuses. Ukitake tells Kaien of a boy who is even younger than Byakuya, who is to be promoted to a seat position in his squad. The boy, who easily slays the 3rd seat of the fifth division, is revealed to be a young Gin Ichimaru, under the watchful and impressed eye of Aizen. The pendulum swings forward 9 years, revealing a glimpse of horrible events yet to come.