Demon Slayer Corps

The Demon Slayer Corps is a organization that has existed since ancient times, dedicating its existence to protecting humanity from Demons.

There are hundreds of Demon Slayers within the organization, however they are not officially recognized by the government. With Muzan Kibutsuji's demise and the near-extinction of the Demon race, the Corps officially disbanded.

Joining
In order to become a Demon Slayer, an individual must pass the Final Selection, a test used as an entrance exam to join the Demon Slayer Corps. During this selection, examinees must survive for seven days on a mountain top infested with Demons without any aid from the outside world.

Candidates who complete the Final Selection are issued the standard uniform, as well as being given the opportunity to choose the ore for their special sword, which is designed to eliminate Demons efficiently. Each new Slayer is also assigned one of a rare species of talking bird for communication purposes.

Salary
Mizunoto are roughly paid around 20,000 yen whereas Hashira are paid as much as they want.

Ranks
Members of the Demon Slayer Corps are separated into ten different ranks. From lowest rank to highest, these ranks are:

Once a Demon Slayer has fully settled into the organization, they are classified as a member of the lowest rank: Mizunoto. They must complete a variety of missions to ultimately climb the ranks and reach the highest Demon Slayer position: Kinoe.

Following the Final Selection, each swordsman has their rank inscribed on their hand through a process called "Wisteria Flower Engraving." As they continue to progress as swordsman, they can check their rank by saying a password and flexing their arm to reveal their status.

Hashira
Within the Demon Slayer Corps, there is a group of elites known as the Hashira. This group consists of the most powerful combatants in the organization.

The Hashira, in accordance with their great strength, are the most highly ranked members of the Corps, second only to the leader of the organization.

In order to become eligible to join the Hashira, a Demon Slayer must either successfully kill 50 Demons or a member of Twelve Kizuki as a Kinoe.

Hashira Training
The Hashira Training is a special training session conducted by the Hashira and undertaken by numerous lower-ranked Demon Slayers. The aim of Hashira Training is to improve all Demon Slayers' physical abilities and overall health, giving the members of the Demon Slayer Corps a better chance of winning the war against Demons.

Each of the Hashira oversees a different part of the training program. Known training includes basic stamina training, flexibility training, quick movement training, sword skill training, pounding training, and muscle reinforcement training.

Hashira Training is extremely strenuous; because of this, a majority of the Demon Slayers view the training session as an everlasting trip in hell, with a few notable exceptions who see the session as a chance to improve themselves.

As a general rule, Hashira must take part in each other's training sessions. It is considered a win-win situation for both the Hashira and the Demon Slayers, as even the Hashira get to improve due to being constantly attacked by wave upon wave of juniors ranked lower than themselves.

Tsuguko
A Tsuguko is a very talented Demon Slayer that has been designated as the successor to one of the Hashira, should that Hashira retire or die. In order to become a Tsuguko, a Demon Slayer can either apply and get accepted, or get scouted by one of the current Hashira.

Kakushi
Within the Corps, there is a cleanup crew known as the Kakushi, where the majority of them have no swordsmanship skills. The Kakushi are responsible for providing first aid to injured Demon Slayers following a large battle, as well as bringing the injured in for proper medical attention.

History
It is heavily implied by Kagaya Ubuyashiki that Muzan came from the same family as him about 1000 years ago. Kagaya states: "This led to the family bloodline being cursed. Every child born in our family was weak, and they died right away. But when our family was about to get wiped from existence, the priest gave us some advice. A Demon came from our bloodline. So you must dedicate your soul to defeating him. And if you do that, your family will not die out. We have received wives from our priests for generations. And our children are more resilient to death now. But nobody in our family has lived beyond thirty." This indicates that the Ubuyashiki family has led the battle against Muzan for almost 1000 years.

Known Members
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Physical Abilities
All Demon Slayers including lower-ranked members have enhanced strength, speed, reflexes, stamina, durability, endurance, agility and mobility, with the Hashira, the physically strongest in the organization, having all aforementioned abilities at beyond superhuman levels.

Sensory Abilities
Higher-level Demon Slayers have extremely keen senses, sometimes even bordering on extrasensory perception. Some Demon Slayers have greatly innately enhanced sensory abilities, like the 5 main senses of sight, hearing, smell, touch and/or taste. They usually use this in combat and even infuse it into their Breathing Styles.


 * * Tengen's hearing ability also extends to echolocation.

Extrasensory Perception
Extrasensory perception, also referred to as the "sixth sense" or "ESP", is a sensory ability where one's senses are able to detect things outside the normal range of perception. Most high-level Demon Slayers, like the Hashira, have basic ESP which they have used to perceive the aura, strength and weaknesses of Demons. However, a shared form of ESP can be accessed through unlocking the Transparent World which allows one to perceive the anatomy and structure of a person and use that to their own advantage in battle.

Demon Slayer Marks
The Demon Slayer Mark is a mysterious supernatural marking that can be unlocked and may appear on the body of a strong Demon Slayer.The most talented Demon Slayers of the Demon Slayer Corps have a chance to develop a mysterious tattoo, scar, or birthmark marking. It resembles the Demon Crests that Demons possess. These marks are referred to as Demon Slayer Marks. It looks somewhat like a tattoo, scar, or birthmark and each Demon Slayer Mark looks unique, relating to the Breathing Style of the bearer.

The true origin of the Demon Slayer Mark is unknown, however, the first recorded occurrence of these markings were in the Sengoku Era, possessed by the first person with a Demon Slayer Mark was none other than the first Breathing Style user, Yoriichi Tsugikuni, who, for unknown reasons, was born with a Demon Slayer Mark. Practically all other swordsmen during the Sengoku Era awakened their Demon Slayer Mark due to the catalyst-like effect of the Mark.

Demon Slayer Marks disappeared for a long time, due to the countless times the Demon Slayer Corps was nearly annihilated, until it reappeared on Tanjiro Kamado, and subsequently, the other Hashira that resonated with his mark.

Total Concentration Breathing
Total Concentration Breathing (の) is an advanced and esoteric breathing technique where a user inhales the maximum amount of oxygen within a specific breath pattern to raise their physical and mental prowess to their utmost limits. The effects include a plethora of enhanced physical and mental abilities, like superhuman physical characteristics (i.e. Strength, Speed, Stamina, Durability and Agility), faster thought processes, concentration and information processing. This technique is also capable of clotting wounds from severe injuries and slowing down the circulation of poison in the bloodstream.

Breathing Styles
Breathing Styles are swordsmanship styles that makes use of an esoteric breathing technique known as Total Concentration Breathing (の) practiced and taught by the Demon Slayer Corps and are used in combat by Demon Slayers.

All known Breathing Styles currently taught within the Demon Slayer Corps are derived from the Sun Breathing, the first one ever created. The majority of known Breathing Styles mimic a certain element of nature (i.e. Flame, Water and Wind) and replicates it with the user's movements, techniques and abilities.

Uniform
The members of the Demon Slayer Corps wear a uniform that is highly durable and light-weight, they are also water-resistant and non-flammable. The uniform cannot be easily damaged by minor Demons. They sport their uniforms with a white belt and hakama pants, also wearing a white long-sleeved collared shirt under the uniform.

The Demon Slayer uniform appears remarkably similar to a Gakuran uniform, consisting of a buttoned shirt with a white framed collar having the kanji for Destroy engraved on the back, a shirt pocket on top of the left breast and white undershirt. It also consists of long, saggy hakama pants strapped by a white buckled belt that can be optionally tucked in with any kind of Kyahan that extends into tabi socks.

Nichirin Sword
Nichirin Swords are special blades used by and made specifically for the Demon Slayer Corps to slay Demons. They are forged from a unique ore that constantly absorbs sunlight, one of the only major weaknesses of Demons. Therefore, decapitation by Nichirin Sword is one of the only ways a human can kill a Demon, the other being the use of a Wisteria-poison coated weapon.

Nichirin Swords take on a distinct color when first drawn by its owner, which is why they are also referred to as "The Color Changing Swords". However, the holder is required to have a certain amount of skill, or the blade will not change color.

Kasugai Crow
Upon passing the entrance exam, each new Slayer is also assigned a Kasugai Crow. These crows posses the ability to speak in full sentences, though their speech is very loud and somewhat limited.

It is the job of these birds to deliver missions to their designated Demon Slayer.

Trivia

 * Rank symbols can be shown at the back of each Slayer’s hand. In the Hashira's case, it’s their title which becomes visible.
 * While all Demon Slayers are assigned a Kasugai crow, Zenitsu was assigned a sparrow. The reason for this is unknown, but oddly enough, Zenitsu is still able to understand the sparrow and receive accurate messages and commands from it.
 * Tanjiro, Zenitsu, Inosuke, Kanao and Genya's final Rank in the series is only divulged in the 2nd Fanbook, the former three all rose up to Hinoe, the latter two rose up to Hinoto.