The Avengers

Hinamori knocks out her guard with Hakufuku and escapes her cell, tearfully clinging to the account in Aizen's letter of who supposedly killed him. Hitsugaya learns from Kōkichirō Takezoe that Hinamori, Renji, and Izuru have all vanished from confinement. Recognizing the escape as Hinamori's Kidō mastery, he grasps that only one motive would push her this far and sets out to save her before she does something irreversible.

Deep inside Sōkyoku Hill's training chamber, Ichigo keeps breaking sword after sword against Zangetsu, who tallies each failure. Yoruichi watches from above and notes that Ichigo now holds his footing even as his blades snap, adjusting to Zangetsu's speed and countering rather than relying on raw power. She admits Urahara was right about the boy's growth. A brief cutaway shows Urahara sneezing at the shop, then suffering through one of Tessai's expired cold remedies.

Once the first day of training ends and Zangetsu reverts to the Tenshintai, Ichigo soaks in the chamber's hot spring and discovers its healing water. Yoruichi joins him, teasing him with her transformations, and reveals that she and Urahara secretly built this space as children and later trained here, and that Urahara was once captain of the Twelfth Division and the founding president of the research institute.

Hitsugaya intercepts Gin and Izuru in the Third Division compound and vows to kill Gin before Hinamori arrives, but she leaps between them and points her sword at Hitsugaya instead, weeping as she demands to know why he killed Aizen. She recounts the letter's claims: that Rukia's execution is a cover to steal the Sōkyoku, whose power could destroy the whole of Soul Society. Hitsugaya insists Aizen would never write such a thing and deduces the letter was forged to make them kill each other. Forced to knock the frenzied Hinamori unconscious, he then sees her hands bleeding from her grip and turns on a grinning Gin, drawing his Zanpakutō as its sheath disintegrates.

Adapting chapters 129 through 131 of the Soul Society arc, the episode intercuts Ichigo's training with the escalating clash between Hitsugaya, Hinamori, and Gin. The anime spreads the letter's contents across Hinamori's escape and adds material such as Aizen writing the letter and a young Rangiku flashback. Censorship covers Yoruichi's hot-spring scene and removes blood from Ichigo's broken-sword injuries. The picture-book segment continues Urahara's misadventures with Tessai's homemade cures.