The Japanese manga series Demon Slayer: Kimetsu no Yaiba is written and illustrated by Koyoharu Gotouge and was adapted into an anime series and movie, becoming (to the surprise of many) one of the highest-grossing franchises of all time, earning $8.75 billion so far. Demon Slayer follows the story of teenager Tanjiro Kamado, whose ambition is to become a demon slayer after the slaughter of his family and his younger sister Nezuko was turned into a demon. As we follow the story, we are taken to Taishõ Japan, where the Demon Slayer Corps (a secret society) has been building up a war against demons.
The demons are former humans who have turned into wonderfully animated villains, like Tanjiro's sister, by Muzan Kibutsuji, who injects them with his blood; the demons feed off humans, which allows them to gain supernatural powers like super strength. Unfortunately, they can only be killed if they are decapitated with weapons made of Sun Steel, which contains poison from a flower that has been in sunlight. So, demon slayers like Tanjiro have a tricky job at hand. Although, demon slayers, despite being completely human, practice special breathing, which they call "breathing styles" that allow them to have similar powers to the demons, which helps them fight.
The Blades of Demon Slayer
In order to fight the demons, they use weapons called Nichirin blades, which are made with Scarlet Crimson, Iron Sand, and Scarlet Crimson Ore, which are all constantly exposed to sunlight, and are collected from the mountains. Seen as they have absorbed sunlight, when the swords are used to kill a demon, they stay permanently killed. When they are decapitated, their bodies turn to ash, although the swords are less effective if used on other parts of the demon's body.
The swords are also sometimes referred to as Color Changing Katanas; this is because when first drawn by its owner, they display a color, which only appears if the owner has presented a certain level of demon fighting skills. The swords come in a variety of colors and in the Japanese show, each color has a different meaning and symbolizes something unique, so let's take a look at each sword color and what they mean.
Amber
The color amber represents sound and is the color of The Sound Hashira. Tengen Uzui's Nichirin's uses cleavers that are connected by a chain, which is a perfectly loud weapon. It is also the color of energy, which comes from Tengen as he swings his cleavers with force and powerful energy to defeat his enemies. He is not afraid of making his appearance always known and can easily cause loud chaos.
White
White blades symbolize mist. There is no other demon slayer like Muichiro Tokito, who is light, airheaded and slick. His mist breathing technique is inspired by the breath of wind and is associated with staying calm and collected like a gentle breeze - the perfect attitude to stay calm when defeating a demon.
Green
The emerald green blade also represents wind breathing and is seen by Wind Hashira, Sanemi Shinazugawa. The abilities that come with his green sword is being fast like a tornado whilst also staying extremely calm. He can also be violent and furious like a hurricane, and any demon that gets in his way does not stand a chance.
Black
Black is the most mysterious color of all the blades, and is held by the main character, Tanjiro. It is a rare blade and represents the sun; it also holds a theory that the demon slayers who own this sword are not to live a long life. Black swords are also supposed to hold all the colors, which means Tanjiro is to find his way through all colors and breathing techniques. It is also said to absorb the most sunlight, so it is the strongest sword against the demons.
Blue
Blue is the color for water, and is one of the first blades that is shown to us in the series. Giyu Tomioka, the Water Hashira uses the breath of water technique to defeat the demons, which makes his movements fluid, fast and seem effortless like slow ripples in the water, and is able to kill demons in one smooth swish of his blade, making him one of the most respected demon slayers.
Red
Red is a threatening color and symbolizes fire and flames. Kyojuro Rengoku uses a red blade and is dangerous, eccentric, and strong, practicing the breath of flames technique to make him powerful and fierce. His strength, both without and within, makes him a brilliant demon slayer, as he is tough, fiery and burns with power when killing demons. His sword is also unique, as it is styled with a decorative flame that runs down his blade.
Yellow
Yellow represents thunder, and is used by Zenitsu Agatsuma. He is as fast as lightning, and strong and powerful like a thunderstorm, which you could not guess by his shy personality and low self-esteem. Although, when he is needed, he explodes and can kill a demon easily. Much like the red blade, his sword is patterned with a lightning bolt that runs down the blade, so he might be shy, but his sword is powerful.
Gray
Gray can symbolize that the holder will master the stone breathing technique, but also that they may not pull a traditional blade. Gyomei Himejima, the Stone Hashira, for example, instead of wielding a sword, holds a giant axe attached to a chain which is still awesome, much like amber. Stone breathing is linked to being able to detach from emotions and be strong and steady, even though Gyomei is emotional and gentle. Yet, he can easily turn it off and become strong, threatening and intimidating when he needs to be.
Pink
Pink of course represents love, and is related to the breath of love technique. Mitsuri Kanroji holds the pink blade and her passionate personality really shines through. Mitsuri even created the love breathing technique, as her muscles are much more dense than normal, which means that she is strong but flexible and dances around killing demons very passionately.