What does Tanjiro’s black sword mean in ‘Demon Slayer: Kimetsu no Yaiba?’

In the world of Demon Slayer: Kimetsu no Yaiba, the demons are powerful beings capable of horrifying strength and cellular regeneration, with their only weakness being the sun. The only one capable of defeating them is the Demon Slayer Corps, an organization of warriors tasked with protecting Japan and eliminating the demon threat once and for all. In order to do that, each Demon Slayer is armed with a special sword called a Nichirin Blade, which is forged from a unique ore that constantly absorbs sunlight and is capable of killing a demon.

When an aspiring Demon Slayer passes the Final Selection exam, they are gifted with their own personal Nichirin Blade. These special blades usually take on a distinct color when first drawn by their owner, making the look of each blade unique. With so many Demon Slayers, there have been a variety of colors that the Nichirin Blades have taken, and each one has been said to provide special properties to a blade. 

So far, we’ve seen the Water Hashira Giyu Tomioka’s blue Nichirin Blade, the Flame Hashira Kyojuro Rengoku’s red blade, and the yellow color of Zenitsu Agatsuma’s Nichirin Blade. Naturally, based on their properties, a fan can easily guess the elemental properties of the respective colors: yellow is for lightning, red is for fire, and blue is for water. But what about Tanjiro Kamado’s black Nichirin Blade? What does that mean?

When Tanjiro first received his Nichirin Blade, the swordsmith responsible for creating Nichirin Blades, Hotaru, and Tanjiro’s teacher, Urokodaki, both believed that it would turn red due to his burgundy hair and eyes. They even informed Tanjiro that the color was a stroke of good luck.

Fans keeping up with the series up to that point expected the Nichirin Blade to turn blue like Giyu Tomioka’s, seeing as both Tanjiro and the Giyu utilize the Water Breathing Style. However, after Tanjiro wielded the blade for the first time, it did the unexpected: it turned pitch black.

What does a black Nichirin Blade mean?

Outside of the color being very rare, not much is known about the properties or symbolism of the black Nichirin Blade. In the series, it’s said that the color is considered to bring bad fortune and that its wielder will eventually die young. However, as it is with any beloved show, Demon Slayer fans have come up with their own theories as to the meaning behind the black blade. One theory suggests that Tanjiro’s sword turning black is connected to his time selling charcoal while his family was still alive. Fans who support the theory even point out that the color is a reflection of his namesake. According to Anime Hunch, the kanji for “tan” means charcoal, and the first half of his last name, “kama,” refers to a Japanese furnace that is used with charcoal.

After watching Demon Slayer: Mugen Train, many fans are supporting a different theory, one that actually came from the Flame Hashira, Kyojuro Rengoku himself. During the film, Rengoku briefly recounts the five basic types of Breathing Styles known in the Demon Slayer’s history ⏤ Water, Flame, Thunder, Wind, and Stone ⏤ and mentions that a black Nichirin Blade signifies a user who can’t find one breathing style to stick to. It actually makes sense, considering that Tanjiro uses both Water Breathing and Hinokami Kagura, a flame dance that utilizes the forgotten art of Sun Breathing ⏤ a feat considered very rare even for the Hashira of the Demon Slayer Corps.

What is Sun Breathing?

In the first episode of the Demon Slayer: Entertainment District Arc, Rengoku’s father informs Tanjiro that Sun Breathing is the original Breathing Style that all others are derived from and the strongest one of them all. Because of this, fans have also theorized that Tanjiro is actually a user of the Sun Breathing style, which allows him to utilize more than one Breathing Style. 

And since it was commonly known (and even addressed in anime) that black absorbs all colors and is considered a combination of all of them, fans speculate that Tanjiro’s black Nichirin Blade also symbolizes his potential ability in mastering all of the Breathing Styles.

Whether the theories are true or not has yet to be seen, but as the stakes continue to rise in season two of Demon Slayer, there’s a good chance that fans will find out more about Tanjiro’s abilities and the significance of his black Nichirin Blade. Stay tuned, as the battle is currently raging across screens in the newest episodes of the Demon Slayer: The Entertainment District Arc on Crunchyroll and Funimation.