is bleach episode 30 filler?

4th Division 7th Seat Hanatarō Yamada guides Ichigo Kurosaki and Ganju Shiba through the canal network underneath the Seireitei, and when Ganju admits that he never would have thought to use it like this, Hanatarō explains that the network spans the entirety of the Seireitei, allowing them to go anywhere they like unimpeded. Though Ganju points out that the canals seem easily accessible due to the entrance being underneath a tile, Hanatarō dismisses the idea of them being caught by the Shinigami.

Upon being asked by Ichigo why he thinks this, Hanatarō reveals that the only ones who fully comprehend the complex network are the members of the Fourth Division who specialize in relief and aid.