is demon slayer: kimetsu no yaiba episode 20 filler?

Tanjiro braces himself for death, when Rui unravels his Blood Demon Art. As his life flashes before his eyes, he remembers his father's kagura dance and unleashes a whole new technique, completely different from Water Breathing.

Hinokami Kagura: Dance... Knowing that this move could mean killing each other, he uses his new move to slice off Rui's head.

As Tanjiro crawls towards Nezuko, who lies on the ground, riddled with wounds, someone appears before him…