What Are Nichirin Swords Made Of In Demon Slayer?

Daksh Chaudhary
Apr 26
3 min read

In Demon Slayer, Nichirin Swords are the main weapon used by the Demon Slayer Corps to defeat demons. These special blades can cut through a Demon’s tough flesh and even cancel out their regeneration. But what exactly are the Nichirin Swords made of, and why do they work so well against Demons?

Nichirin Swords look like ordinary katanas, but they hold a secret. Each blade is forged from a rare ore that absorbs sunlight. Since sunlight is lethal to Demons, the sword itself carries that power. When a Demon Slayer swings a Nichirin Sword, they’re not just cutting the Demons, they’re unleashing concentrated sunlight.

Check out our YouTube Short to learn more about how Nichirin Swords are made in Demon Slayer.

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The Scarlet Ore: A Secret Metal Nichirin Swords Are Made Of

Nichirin swords are made of Scarlet Crimpson Iron Sand and Scarlet Ore, a special metal found only on mountains that are bathed in sunlight year-round. This ore absorbs sunlight like a sponge, which is why it’s deadly to Demons. Think of it as a solar battery, when forged into a sword, it stores that sunlight energy, letting it burn Demons from the inside.

But here’s something interesting - Scarlet Ore is alive (kind of). Swordsmiths say it has a “spirit” that reacts to the wielder’s heart. That’s why the swords change color when a Slayer first holds them. The ore isn’t just metal, it’s a partner in the fight against Demons.

The Forging Process: Fire, Hammers, And Rituals

Forging a Nichirin blade isn’t just smacking metal with a hammer. It’s a sacred art passed down for centuries. Swordsmiths like Hotaru Haganezuka use special flames and rituals to awaken the ore’s power.

First, they smelt the Scarlet Ore at super-high temperatures. Then, they fold and hammer it hundreds of times to remove impurities. This makes the blade nearly unbreakable. Finally, they quench it in water mixed with crushed gemstones - a ritual said to tame the ore’s wild energy. The result? A blade that’s sharp enough to cut boulders and tough enough to clash with Upper Moons.

The Color Change: Why Blades Glow And What It Means?

When a Demon Slayer first grips their Nichirin sword, it changes color based on their personality, Breathing Style, or soul. Tanjiro’s turns black, a rare shade that symbolizes the sun’s core. Mitsuri’s turns pink, reflecting her loving heart. Kyojuro’s? Bright red, matching his fiery spirit.

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But the color isn’t just for looks. It shows how the sword channels the Slayer’s power. For example:

Red blades can temporarily slow Demon regeneration (like Kyojuro’s).
Black blades are unpredictable but pack raw power (like Tanjiro’s or Yoriichi’s).
Rainbow blades (like Muichiro’s misty blue) enhance specific Breathing Techniques.

The color is a bond between Slayer and sword; proof they’re meant to fight together.

The Swordsmith Village: Guardians Of The Secret

Only the Swordsmith Village knows how to make Nichirin swords. Hidden deep in the mountains, this place is protected by traps, illusions, and the Mist Hashira himself. The villagers aren’t just blacksmiths, they’re monks, guarding ancient knowledge about the Scarlet Ore and the Demons’ weakness to sunlight.

The most skilled smiths, like Tecchin Tecchikihisa, can even reforge broken blades. When Tanjiro’s sword shattered fighting the Hand Demon, it took weeks of work (and a lot of Hotaru’s yelling) to fix it. Without the village, the Demon Slayer Corps would’ve fallen centuries ago.

Final Verdict: Nichirin Swords Are The Heart Of Demon Slayer

Nichirin swords aren’t just metal, they’re sunlight given shape. The Scarlet Ore’s power, the smiths’ craftsmanship, and the Slayers’ spirits all fuse into a weapon that’s alive. Every swing carries the weight of centuries of tradition, and every color tells a story.

But here’s the real secret: The swords work because the Slayers believe they work. Their courage, love, and rage fuel the blades as much as the ore. They’re the heart of the Demon Slayer Corps, and the reason Demons fear the dawn.