Nichirin blades are special blades forged from a unique ore that constantly absorbs sunlight. Since this is one of the only major weaknesses of demons, these blades are used by demon slayers to kill demons. A demon slayer’s sword will take on a colour when first, with each colour having a meaning. There’s a variety of colours that the swords can have, and it’s said that each colour imparts certain properties to the blade related to the owner’s breathing style. There are 14 blade colours seen throughout the series, as each correlate to one of the 14 breathing styles demon slayers use. This post covers 7 possible colours that a nichirin blade can be.

Please be aware that this post contains spoilers for the Demon Slayer manga.

White

Mist style users have white blades, such as the Mist Pillar of the Demon Slayer Corps Muichiro Tokito. The Mist Breathing Style mimics mist and vapour, especially its obscurity.
Users replicate this with their movements, techniques and swordsmanship to invoke swift strikes and movements. They perform these in a way that confuses and obscures their opponent’s sense and surroundings. When used properly, Mist Breathing users visualises light blue mist and vapour emulating from their sword and/or their body.

2. Green

Wind style users have green blades, such as the Wind Pillar Sanemi Shinazugawa. The Wind Breathing combat style and breathing techniques mimic wind and air. Users imitate powerful air torrents, tornados and whirlwinds with their movements, techniques and swordsmanship.
The forms and techniques of the Wind Breathing Style make use of the air around the user to generate powerful wind gushes to enhance striking power. When this style is used property users will visualise wind in a light shade of green coming from their sword and/or their body.

3. Grey

Grey swords are owned by users of the Stone Breathing combat style and breathing techniques, such as the Stone Pillar of the Demon Slayer Corps called Gyomei Himejima. This style is known for its techniques, movements and swordsmanship that are study and solid like stone. Unlike the traditional Nichirin Blade though, the Stone Pillar a hand-axe with a spiked flail attached to it via a long grey chain. (This weapon is still made from the same unique ore used to make Nichirin Blades, but with a superior technique).
The forms and techniques of this style utilise the ground beneath the user and their surroundings to create powerful offensive and defensive attacks. When used properly, users of the Stone Breathing style will see cracks in the earth around their sword and/or body.

4. Pink

Pink swords are owned by users of the Love Breathing Style. Mitsuri Kanroji, the Love Pillar of the Demon Slayer Corps, is the only person capable of using this style.
Kanroji developed the style thanks to her body’s unique constitution. She’s flexible, agile and the fastest of all the pillars, but possesses inhuman strength due to her having muscles 8 times more dense than normal without losing speed. Unlike other Breathing Styles, the Love Breathing Style is based upon emotions rather than elements or natural phenomena. Because of this, techniques in this style are whip-like and require superhuman flexibility, dexterity, agility and speed. When used properly, users will see pink strikes emanating from their sword and/or body.

5. Indigo-Grey

Indigo-Grey swords are owned by Beast Breathing Style users. This style was created by Inosuke Hashibira and is derived from the Wind Breathing Style. Inosuke developed this style after living in the mountains, and it enhances his sense of touch.
The Beast Breathing combat style and techniques imitate beasts and wild animals, particularly their unpredictability and wild nature. Most techniques and forms are known to be straightforward but with unpredictable and wild-seeming attacks and movements. When used properly, the user sees light blue and grey claws and hears loud beast roars coming from their sword and/or body.

6. Yellow

Yellow swords are wielded by Thunder Breathing Style users, such as Zenitsu Agatsuma. Zenitsu in particular has a unique blade colours, as his yellow is actually a lightning strike motif running down his blade.
The Thunder Breathing combat and breathing style mimics lighting, electricity and thunder with swift strikes and movements (similar to lighting strikes and the sound of thunder). Techniques and forms are known to involve movements and attacks using blinding speeds to close into targets, and insanely fast movements to overwhelm opponents. When used properly, users will see deep yellow or light blue electricity strike from their sword and/or body.

7. Blue

Blue swords are wielded by Water Breathing Style users, such as the Water Pillar Giyu Tomioka. Blue swords are said to the be the most common colour, since the Water Breathing Style is the most commonly used among Demon Slayers (since it is the easiest for beginners to learn).
The style mimics the flow of water and adaptability of water, which is reflected in users’ movements, techniques and swordsmanship. Techniques involve users bending their body, limbs and weapons similar to the flow of water. When used properly, users will visualise water in a deep shade of blue with white wavy patterns that resemble traditional Japanese paintings of waves from their body and sword.