: The existence of the Soul King and the threat to Karakura Town.
: Hitsugaya and Rangiku set up a communication monitor in her apartment, where she receives news from the Soul Society.
: Captain-Commander Yamamoto reveals Aizen's true goal: to sacrifice 100,000 human souls in Karakura Town to create the Oken (Royal Key). This key would allow Aizen to enter the dimension of the Soul King and overthrow him.
For more details on the series' progression, you can check the Bleach Episode Guide or deep-dive into character histories on the Bleach Wiki .