Bleach Volume 36

A century and ten years before the start of the series, the Visards were originally Soul Reapers in the Soul Society. A Squad Five lieutenant at the time, Aizen learns from his captain Shinji Hirako that Kisuke Urahara is about to become Squad Twelve Captain with the support of Squad Two Captain Yoruichi Shihōin. Despite the animosity towards him by his lieutenant Hiyori Sarugaki, Kisuke manages to win her respect as he recruits an imprisoned Mayuri Kurotsuchi to help turn Squad Twelve into the science-based division it currently is. A few years later, several Soul Reapers began to mysteriously disappear and Squad Nine under Captain Kensei Muguruma and his lieutenant Mashiro Kuna soon investigate. Soon after, a group consisting of Shinji, Soul Reaper captains Rōjūrō "Rose" Otoribashi and Love Aikawa, Squad Eight lieutenant Yadomaru Lisa, and Hachigen Ushōda of Kidō Corps, are dispatched. Despite Yamamoto refusing his request to visit the site, Urahara sends Hyori to investigate in his stead. However, the Shinji's group find Hyori attacked by a hollowified Kensei and Mashiro. They subdue the Hollows, including Hyori, but are suddenly incapacitated by Tōsen with the exception of Shinji as Aizen appears.

Turn Back The Pendulum
Contains chapters Turn Back the Pendulum Parts 1 - 9.