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 each serving a pivotal role in their war against Muzan Kibutsuji.

Overview
A group overseen by their leader Kagaya Ubuyashiki, they are regarded as the most potent swordsmen among the Demon Slayers and sustain the organization itself. 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 and to improve their swordsmanship. Swordsmen who can use the Breath of Flames and Water have become Pillars in every era, no exceptions.

Joining
There are several 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.
 * Pillars are constantly looking for a Tsuguko (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 Nezuko Kamado 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, 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, showed up. A battle between Akaza and Kyojuro Rengoku occurred. As a result of the fight, Akaza fled, but Kyojuro died from his wounds and left an empty Pillar spot.

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

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

Several duels broke out in the Infinity Fortress between demons and slayers. The Pillars and the other demon slayers faced off against many demons who all had equal strength to 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 was killed and absorbed by Doma. Shinobu's younger sister, Kanao and Inosuke then fight Doma immediately after. Zenitsu Agatsuma ran into the new Upper Moon Six, the former apprentice brother Kaigaku and engaged him in a duel to the death, in which Kaigaku had an overwhelming advantage and nearly killed Zenitsu, but Zenitsu managed to behead Kaigaku with a secret technique he created. Elsewhere, Tanjiro and Giyu Tomioka were ambushed by the Upper Moon Three, Akaza. After a long battle, Tanjiro kills Akaza, and the two demon slayers come out victorious, while Muichiro Tokito, Gyomei Himejima and Sanemi Shinazugawa run into Kokushibo, Upper Moon One.

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