Hashira

The Pillars are the nine most powerful swordsmen of the Demon Slaying Corps. As such, they are the organization's top-ranking, most elite soldiers who each serve a pivotal role in their war against Muzan Kibutsuji.

Overview
The group is overseen by their leader Kagaya Ubuyashiki and are regarded as the most potent swordsmen among the Demon Slayers, since their existence literally sustains the entire organization. Those who are of lower rank may be killed at a frightening rate, but each Pillar possesses a distinct Breath Style which is learned from a cultivator or developed through extreme training. The Pillars are all assigned a specific region that they are required to patrol, usually to gather information about the Demons inhabiting the said area and to improve their swordsmanship. Swordsmen who can use the Breath of Flames and Water have become Pillars in every era, with no exceptions.

Joining
There are two known methods to become a Pillar. A record of 50 Demon Kills is required, but the slaying of one of the Twelve Demon Moons also fulfills the requirement. This type of effort requires almost five years worth of training, though the talented might take only two or so years to do so.

Successor
Pillars are constantly looking for a Successor to take their place when they die or retire. A Demon Slayer can become a Tsuguko either by applying and getting accepted, or by being scouted personally by the Pillars themselves. A Tsuguko normally uses the same Breath Style as the Pillar, though this isn't a strict requirement.

Abilities

 * Demon Slayer Marks - Pillars are the only known Demon Slayers (with the exception of Genya Shinazugawa and Tanjiro Kamado) who are capable of displaying these markings when they are fighting Demons. All of the living Pillars except for Obanai Iguro, have successfully been able to emit these markings which are said to enhance one's physical and tactical abilities.
 * Full Focus Breathes - A tactical skill which sets Pillars apart from ordinary Demon Slayers. Pillars, as well as Kanao Tsuyuri, Tanjiro, Zenitsu Agatsuma, and Inosuke Hashibira, use this breathing method to generate an oxygen supply in their blood and strengthen their muscles. It gives them the power and stamina needed to combat demons without changing their physical form.

History
After the fight with Lower Moon One, Enmu, the Upper Moon Three, Akaza, shows up. A battle between Akaza and Kyojuro Rengoku occurs, and as a result of the fight, Kyojuro dies from his wounds and leaves an empty Pillar spot, while Akaza flees with his life.

Not long after that, Tengen Uzui takes Tanjiro and his group to a mission in the Red Light District. There, they encounter Upper Moon Six, Daki and Gyutaro. As a result of their fight, Daki and Gyutaro died and Tengen lost his left eye and arm, forcing him to retire and leave a second vacant Pillar position. However, despite his forced retirement, Tengen (along with his wives) still assist with the Demon Slayer Training Program.

After Muzan Kibutsuji breaks into the Ubuyashiki Manor, he is attacked by Gyomei Himejima, the Stone Pillar, in an attempt to slay him, but Muzan escapes into the Dimensional Infinity Fortress with several other Demon Slayers chasing after them, only for them to be separated by Nakime, the current Upper Moon Four.

Several duels break out in the Infinity Fortress between Demons and Demon Slayers. The Pillars and the other Demon Slayers face off against many Demons who all have equal strength to that of a Lower Moon. Shinobu Kocho attempted to kill the Upper Moon Two Doma, who was responsible for the death of her older sister. However, she is killed and absorbed by Doma. Shinobu's younger sister, Kanao, and Inosuke then fight Doma immediately after and were able to defeat the Demon thanks to the poision inside Shinobu's body. Zenitsu runs into the new Upper Moon Six, the other former apprentice of his master, Kaigaku, and engages him in a duel to the death, in which Kaigaku has an overwhelming advantage and nearly kills Zenitsu, but Zenitsu manages to behead Kaigaku with a secret technique he created. Elsewhere, Tanjiro and Giyu Tomioka are ambushed by the Upper Moon Three, Akaza. After a long battle, Tanjiro beheads Akaza, although the Demon manages to survive this attack, and eventually the battle is won by the Upper Moon committing suicide. The two Demon Slayers come out victorious, while Muichiro Tokito, Gyomei and Sanemi Shinazugawa run into Kokushibo, Upper Moon One.

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