No, Nichirin Blades, as depicted in the "Demon Slayer: Kimetsu no Yaiba" series, are not real. They are fictional weapons created for the story's universe.

While the concept of Nichirin Blades draws inspiration from traditional Japanese swords, such as katanas, the specific abilities, colors, and properties attributed to Nichirin Blades in the series are purely fictional. They are artistic creations within the context of the manga and anime.

In reality, traditional Japanese swords like katanas are historical weapons with their own rich history and craftsmanship, but they do not possess the fantastical elements or unique abilities depicted in the series.