Kyogai

Kyogai was a member of the Twelve Demon Moons, having held the position of Lower Moon Six.

History
Sometime after becoming a Demon, Kyogai was lectured by an unknown individual over the quality of his writings. This person noted that he had become boring, only beating his drum and not leaving his house, and didn't have the skills to teach people. As he left, the individual stepped on one of the Demon's papers, causing an irate Kyogai to kill him.

While still a member of the Twelve Demon Moons, Kyogai slowly lost the ability to eat humans. He was visited by Kibutsuji Muzan, who removed his number due to the Drum Demon having reached his limit. Because of this, Kyogai obsessively began his quest to rejoin the Twelve Demon Moons.

At some point, Kyogai captured Teruko and Shoichi's older brother, Kiyoshi, due to him possessing "rare blood", and took him to the Drum House. Before he could eat him, he was attacked by two other Demons who were also after Kiyoshi's rare blood, suffering an injury that dislodged the drum from his back.

Drum House Arc
As Kamado Tanjirou and his group attended to an injured boy thrown out of the Drum House, Kyogai played the drum on his left shoulder. He passed by the room Tanjirou and Teruko were in, annoyed by the presence of all the intruders in his territory, slapping the drum on his right shoulder when the former attempted to attack him, which changed the orientation of the room. With the arrival of Hashibira Inosuke, the Drum Demon struck his right shoulder again, then once more, his opponent deftly keeping his balance and using the other two as footholds. As Tanjirou and Inosuke quarreled, Kyogai struck the drum on his stomach twice, each time launching a slashing claw attack. He then struck his shoulder drums multiple times, sending his adversaries flying in a disorganized mess. As he stepped in the direction of Inosuke, he, along with everyone else, were transported into different rooms.

Elsewhere, Kyogai obsessed over obtaining "rare blood", his right eyeball rolling forward to reveal that he was once a member of the Twelve Demon Moons. He happened upon Tanjirou in the course of his wandering, striking a drum to flip the room upside down, striking another to initiate his claw attack, along with a slew of others to disorientate his opponent. He growled menacingly as Tanjirou got up, despite the combination of new and old injuries.

Continuing to strike his drums to keep his Demon Hunter opponent away from him, memories from the past caused Kyogai to snap, initiating his Rapid Drumming technique and sparking a maelstrom of effects. Apart from a scrape on the chin, this effort was fruitless, Tanjirou evading a collection of manuscripts that fell from a shelf on the ceiling, which surprised the former Demon Moon. Despite his continued slash attacks and orientation changes to the room, Kyogai's opponent continued to close on him by using a certain Breath of Water technique. The former Demon Moon was further surprised when Tanjirou complimented his Blood Demon Art, before being decapitated. He asked the youth if he really thought his techniques were powerful, which was confirmed, but he was told that eating humans was unforgivable. Fading into oblivion, Kyogai reflected on how Tanjirou had seen the value in all of his work, tears running down his face.