What makes a blue Nichirin blade different from other colors in the series?
Updated Feb 2026
In Kimetsu no Yaiba, the color a Nichirin blade takes on reflects the wielder's breathing style affinity. A blue tone is closely associated with Water Breathing, the technique practiced by Tanjiro Kamado early in the series and mastered by the Water Hashira, Giyu Tomioka. The color is said to emerge when the blade's special ore reacts to the user's innate qualities. In replica form, this distinctive blue is achieved through careful surface treatment on the high carbon steel, reproducing the gradient effect visible in the anime. It is one of the most recognizable blade colors in the franchise and a natural starting point for any Demon Slayer collection.