is demon slayer: kimetsu no yaiba episode 48 filler?

Muichiro rescues Kotetsu, who was being attacked by a goldfish demon. He tries to rush to the village where the crisis is looming; however, he is asked by Kotetsu to rescue Haganezuka and Kanamori, so he begins heading their way instead.

Meanwhile, Tanjiro, Nezuko, and Genya are facing off against the demons, who have split into four separate bodies. Separated from the rest, Tanjiro alone continues to fight a close battle with the demon with a mark of the word "Joy"...