end of hypnosis8 (the Transfixion)

The chapter opens on memories of Kaname Tosen's friendship with Sajin Komamura, from their first meeting, where the masked wolf startled the ever-perceptive Tosen by hiding his presence, to Tosen ushering his friend into the Fifth Division to serve under Aizen. In the present, on Sokyoku Hill, Aizen catches Komamura's blade bare-handed and shrugs off a blow from the giant fist of Tenken, prompting the enraged captain to demand an explanation for the betrayal.

When Komamura moves to release his Bankai, the Aizen standing beside Tosen dissolves as an illusion, and the true Aizen materializes to entomb Komamura in Kurohitsugi, a towering black coffin skewered by lances, cast without a single word of incantation. Ichigo reels at the gulf in strength between two captain-class fighters, while Gin marvels at the feat and Aizen dismisses it as barely a fraction of the spell's real force. Retrieving Rukia from Gin, Aizen lays out the rest of his scheme: he slaughtered the Central 46 soon after Rukia was located, masked the empty chamber with his hypnosis so it seemed still in session, and hid with his accomplices in the underground assembly hall to issue false decrees, dispatching Byakuya and Renji to seize her, ordering her gigai destroyed, and setting her execution by the Sokyoku so the flames would vaporize her soul and free the Hogyoku. He explains that he mined the vast archive of the Daireishokairo for Urahara's research as a backup. Triggering a capsule, Aizen raises spear-like pillars, reshapes his arm into a blade, and plunges it into Rukia's chest to draw out the tiny orb, leaving her soul unharmed. Judging her useless, he lifts her by the collar and commands Gin to finish her, but Shinso's lunging blade is halted when a still-wounded Byakuya throws himself into its path to shield his sister.

The eighth entry in the end of hypnosis arc sits in the twentieth volume of the series. Its opening flashbacks trace how Tosen and Komamura came to know one another and enter the Gotei 13, setting up the tragedy of Tosen's betrayal. The chapter was adapted into the sixty-second anime episode.