You can read Bleach 525 at this online popular manga site. Here is the summary of Bleach chapter 525: While being hurled across the arena, Zaraki struggles to discover why he keeps suddenly losing consciousness in the middle of the fight. He feels nostalgic as it happened once before.
Meanwhile, Unohana thinks back to a time when she was on a mission in Rukongai. Her subordinate arrives at her presence and informs her that no matter how much he searched, he will be able to find a single person in Rukongai strong enough to satisfy her. Unohana remarks that he realized her real intentions. The subordinate states that the mission is to "subjugate the warriors on the outskirts of Rukongai to keep the peace in Seireitei", and that if there wasn't such a reason there would be no need to send someone like her. He further tells her that he considers that the size of the mountain of corpses beside them represents the amount of her displeasure. Then, a young Zaraki suddenly appears on top of the mountains. Zaraki and Unohana immediately face off, and Unohana states she never thought she'd find so much pleasure facing a child.
