Twelve Kizuki

The Twelve Demon Moons (十二鬼月) are a group of twelve powerful Demons under Muzan Kibutsuji's command, who have all been given a portion of his blood which have augmented their powers.

Structure
The Twelve Demon Moons are divided into two groups, the Upper Moons (上弦) and the Lower Moons (下弦). Each has their number engraved into their eye, with the Lower members having it in only one, whereas Upper members have it in both. This number signifies how strong the member is, with Upper Moon One being the strongest and Lower Moon Six being the weakest overall, and while the exact relationships between the two groups are unclear, it is said by Muzan himself that the Upper Moons despise the Lower Moons.

The Twelve Demon Moons have been given three tasks to complete by Muzan's command:
 * 1) To find the Blue Spider Lily (the key ingredient of the experimental medicine that made Muzan a demon); but since Muzan's discovery (via Hantengu Chapter 126) that Nezuko is sun-proof, he has decided that the Upper Moons should focus on capturing her and bring her to him.
 * 2) To destroy the Demon Slaying Corps.
 * 3) After the failure, to find the Blue Spider Lily or destroy the Demon Slaying Corps. In over a thousand years, he has decided that the demons should serve him with a suicidal devotion to ensuring success.

The Pillars of the Demon Slaying Corps have killed numerous Lower Moons over the years, while the Upper Moons have killed (and eaten) various Pillars as proof of their strength. Since the members of the Upper Moons have not changed for over a hundred years, but at the same time, the members of the Lower Moons have been killed and replaced many times over. Kibutsuji Muzan decided to dismantle the Lower Moons after the most recent failure, the death of Rui (Lower Moon Five), by summoning the remaining Lower Moons to a meeting. Muzan then proceeded to kill the unnamed Lower Moons Two, Three, Four, and Six after their weakness was revealed, sparing only Enmu (Lower Moon One) by giving him a chance to redeem himself by killing a pillar with an injection of his blood. But with Enmu's death by the hands Tanjirou, the Lower Moons are officially disbanded with all of their members dead.

Overview
The first of the Twelve Demon Moons that was encountered in the series was Lower Moon 6, Kyogai. Who is later slain in battle by Tanjiro Kamado. Tanjiro and his companions would shortly thereafter face-off against Lower Moon 5, Rui, who was manipulating a group of demons to forcibly act as family figures to himself and to also assist with the killing of Demon Slayers. Tanjiro would almost manage to behead Rui but unfortunately, the demon outwitted the young slayer by using his threads to cut off his own head. He is later saved by the timely arrival of the Water Pillar, Giyuu Tomioka, who swiftly beheads Rui for good. Rui's destruction would later prompt Muzan Kibutsuji to lose his entire faith in the group's ability and proceeded to dismantle the remaining Lower Moon members by killing all except for Upper Moon 1, Enmu.

After the deaths of Gyutaro and Daki (Upper Moon Six), he summoned the remaining members of the Upper Moons and gave Hantengu and Gyokko (Upper Moons Four & Five) a mission to exterminate the Swordsmith's Village, to reduce the power of the Demon Slaying Corps. By removing their ability to fight on par with the demons without swords. Both Hantengu and Gyokko were slain, but not before Hantengu witnessed (before dying) Nezuko standing in the sun; which has changed Muzan's interest into devouring Nezuko to become perfect.

After his attack on the Ubayashiki Manor, Muzan escaped into the Infinity Fortress thanks to Nakime. It's revealed that Nakime has replaced Hantengu as the new Upper Moon Four and that Kaigaku (a former demon slayer and apprentice brother to Zenitsu) became the new Upper Moon Six to replace Gyutaro and Daki, after an encounter with Kokushibo. It's still currently unknown who the new Upper Moon Five is. Zenitsu later ran into Kaigaku and had a duel to the death with his former brother, resulting in Kaigaku's death and Zenitsu almost dying.

Shortly after arriving in the Infinity Fortress,Shinobu Kocho would stumble upon Upper Moon 2, Doma, feasting on his female followers in his chamber. A single woman survived, only to be mercilessly slain by Doma, despite Shinobu's hasty efforts to save her. Battle commenced between the Pillar and Upper Moon