is demon slayer: kimetsu no yaiba episode 40 filler?

As Nezuko rushes to aid Tanjiro during a critical moment, her appearance begins to gradually take on a demon form as she sustains Daki’s attacks. Nezuko is able to overpower Daki as her demon form accelerates; however, she turns her attention to innocent bystanders injured during the battle and charges towards them.

While Tanjiro attempts to restrain Nezuko, Daki draws near...