Tanjiro meets a fellow Final Selection survivor, Zenitsu Agatsuma, on his way to his next assignment. Tanjiro hears the mysterious sound of a tsuzumi.
The owner of the tsuzumi literally rocks the house as entire rooms rotate at the whim of his instrument, separating Tanjiro from Zenitsu in a house of horrors - one of which is a man with a boar for a head.
Tanjiro's world keeps spinning as Kyogai's tsuzumi commands gravity itself with every beat, driving Tanjiro up the wall. Literally.
Kyogai defeated at last, Tanjiro finds Zenitsu battered and worn and holding an unconscious Nezuko before the dual Nichirin Swords of the man in the boar mask.
Tanjiro, Nezuko, Zenitsu and Inosuke travel north-northwest to spider-infested Mt. Natagumo where they find fellow Demon Slayers in a bit of a bind.
Inosuke and Tanjiro run into more hostile human-marionettes and struggle to find a way to save them without harming them, but it looks like Tanjiro has an ace up his sleeve.
Tanjiro discovers a possible cure for Nezuko while Zenitsu faces his fears, only to find a face he fears.
Tanjiro is blown away by the Father Spider Demon's overwhelming power and meets a dysfunctional familial dilemma that launches him in a battle against the sadistic demon Rui.