is bleach episode 21 filler?

In the Seireitei in Soul Society, several alarm tiles slot into place as a voice declares that a distortion has been detected in the western Rukongai and alerts the Shinigami, who proceed to run toward the source of the disturbance as 6th Division Lieutenant Renji Abarai wonders what is going on. Meanwhile, in the Dangai, Ichigo Kurosaki and his friends run along the path.