Bleach: Season 1, Episode 129

1 - 129: The Swooping Descent of the Dark Emissary! The Propagation of Malice

The mysterious Arrancar has the ability to duplicate itself, and the team must find the original copy which sends messages to its duplicates in order to destroy it. They know it must somehow be connected to the strange tune. Shouta finds his sister, but she runs away back to the park without warning.