Nichirin swords (Nichirin-tō) are the weapons used by the Demon Slayer Corps in Kimetsu no Yaiba. In the series, they are forged from a special ore found on mountains bathed in sunlight year-round. The ore absorbs sunlight, making the blades the only weapons capable of permanently killing demons. Each blade changes color when first drawn by its owner, with the color determined by the wielder's Breathing Style and combat abilities.
