Demon Moons - Kimetsu no Yaiba (Demon Slayer)
The Twelve Demon Moons are Muzan Kibutsuji's elite group of Demons. They are the twelve most powerful Demons under his command and are his personal servants. Each of the Twelve Demon Moons have received some of Muzan Kibutsuji's blood and the stronger they are the thicker his blood will be, which further increases their abilities. The Twelve Demon Moons are given three main tasks:
Finding the Blue Spider Lily. This is a key ingredient in an experimental medicine made by a genius doctor in the Heian period. A prototype of this medicine is what turned Muzan Kibutsuji into a Demon.
Finding the location of the Ubuyashiki family’s base of operations and destroying the Demon Slayer Corps. Muzan Kibutsuji’s relatives, the Ubuyashiki family, are the leaders of the Demon Slayer Corps, which is a great thorn in his plans.
Finding Nezuko. After discovering that Nezuko is able to walk in sunlight and is immune to the Demon’s greatest weaknesses, Muzan Kibutsuji wishes to absorb her so he would be able to walk under the sun as well.
Overview
The Twelve Demon Moons are split into two groups, the Upper Moons and the Lower Moons. The demons belonging to the Upper Moons are much stronger than those in the Lower Moons. The Upper Moons have their number and rank engraved into both of their eyes while the Lower Moons only have one of their eyes engraved. The number engraved in their eyes represents how strong each Demon is. Upper Moon One is the strongest while Lower Moon Six is the weakest. The Upper Moons hate the Lower Moons and there is a significant difference in strength between the two groups. If a Demon of lower ranks gets strong enough they will be able to challenge a Demon of higher rank by a 'Blood Battle' and if the challenger wins, they will be able to take over their position. If a Demon is kicked out of the Twelve Demon Moons, then Muzan Kibutsuji will demote the Demon by slashing their eyes, nullifying the rank they were given. One example of such a Demon is Kyogai, who had reached his limit and couldn't eat any more humans to be able to grow stronger. As such, he was kicked out of the Twelve Demon Moons which could still be seen through the 'X' shaped scar on his pupil. Over the years, the Pillars of the Demon Slayer Corps have been able to kill many Lower Moons, but the Upper Moons have killed and eaten many Pillars in return. It has been said that no one has been able to kill an Upper Moon in a hundred years, since Upper Moon Six Daki and Gyutaro were killed.
”The demons with Muzan’s thick blood coursing through them are demons that have gained a massive amount of strength from Muzan himself.”
—Tamayo to Tanjiro, Demon Slayer Chapter 15
Upper Moons
Upper Moon One: Kokushibo
Upper Moon Two: Doma
Upper Moon Three: Akaza
Upper Moon Four: Nakime
Former Upper Moon Four: Hantengu
Former Upper Moon Five: Gyokko
Upper Moon Six: Kaigaku
Lower Moons
Lower Moon One: Enmu
Lower Moon Two: Rokuro
Lower Moon Three: Wakuraba
Lower Moon Four: Mukago
Lower Moon Five: Rui
Lower Moon Six: Kamanue
Former Lower Moon Six: Kyogai
History
The first Twelve Demon Moon to appear is the former Lower Moon Six, Kyogai who got demoted after reaching his limit. Tanjiro Kamado confronts him and is able to decapitate him. Next to appear is Lower Moon Six Rui who is considerably stronger and requires the Water Pillar Giyu Tomioka to decapitate him. After Lower Moon Six Rui was killed, Muzan Kibutsuji calls for a meeting between the Lower Moons and decides they are useless and gets rid of them (with the exception of Enmu), as the Lower Moons have shown little success when going up against the Demon Slayers Corps. In the end, the only survivor of the Lower Moons, Enmu, battles against Fire Pillar Kyojuro Rengoku, Tanjiro Kamado, and his companions and is slain.
The first Upper Moon Demon to appear is Upper Moon Three Akaza, who is worlds apart in strength and easily kills the Fire Pillar Kyojuro Rengoku.
The next Upper Moon to appear is Upper Moon Six Daki and Gyutaro
who are discovered to share a body. While on the verge of death, the Sound Pillar Tengen Uzui, Tanjiro Kamado, and his companions were able to decapitate both Demons, killing them. After the death of an Upper Moon, Muzan Kibutsuji summons the rest of the Upper Moons for a meeting and expresses his disappointment with the lack of information for his tasks. He then instructs Upper Moon Four Hantengu and Five Gyokko to confirm some intel. The two Upper Moons then infiltrate the hidden blacksmith village and fight with the Mist Pillar Muichiro Tokito, Love Pillar Mitsuri Kanroji, Tanjiro Kamado, Nezuko, and Genya Shinazugawa, who are able to work together to slay the Upper Moons.
When Muzan Kibutsuji discovered that Nezuko is now able to walk under the sunlight he sets his priority to capture her as number one. After an attack on the Ubuyashiki family, Muzan Kibutsuji escapes into the Dimensional Infinity Fortress, where the rest of the Upper Demon Moons fight with the many Demon Slayers who entered. After various battles within the Dimensional Infinity Fortress the remaining Upper Moons are killed by the hands of various Demon Slayers. The last member, Upper Moon Four Nakime, ends up being killed by Muzan Kibutsuji himself to stop the Dimensional Infinity Fortress from being controlled by his enemies.