Kyogai

First appearance. The Drum Demon of the Tsuzumi Mansion, a discarded Kizuki.

Kyogai revealed as Former Lower Rank Six. The Drum Demon was cast out of the Twelve Kizuki when Muzan judged his Blood Demon Art had stopped growing. His rejected manuscripts mirror the rejection.

Beheaded in the rotating rooms of his own mansion. Tanjiro acknowledges his Blood Demon Art as incredible before the killing stroke. Killed by Tanjiro Kamado.

Tanjiro reads the rotating rooms, honors the Drum Demon's art out loud, and takes his head.

Kyogai was excommunicated from the Twelve Kizuki when his Blood Demon Art stopped evolving. Demons are discarded the moment they stop being useful to Muzan.