is bleach episode 173 filler?

Ichigo Kurosaki is woken abruptly by the frantic cries of Kenryū and Enryū, who break through his window, informing him that Rurichiyo has gone missing once more. Meanwhile, at the entrance to the Kasumiōji compound's Senkaimon, Rurichiyo sneaks past the guards, before encountering Gyōkaku Kumoi, who tells her vassals to return her to the palace via palanquin.

When her procession leaves, Kumoi tells Hanza to come out of hiding. He instructs him to use this rare opportunity to assassinate Rurichiyo while her guards are absent.