is demon slayer: kimetsu no yaiba episode 46 filler?

Tanjiro encounters Mist Hashira, Muichiro Tokito, and Kotetsu, a boy from the village, arguing. Muichiro is demanding that a “certain key” be handed over to him from Kotetsu.

Being unable to look on in silence, Tanjiro intervenes to speak on behalf of Kotetsu; however, Muichiro refuses to listen. According to Kotetsu, the key is used to operate a battle-type Mechanical Doll, Yoriichi Type Zero, that mimics the movement of a certain real-life swordsman...