What is the most evil katana?

Could you elaborate on what you mean by "the most evil katana"? Are you referring to a specific historical weapon, a work of fiction, or perhaps a metaphorical representation of something sinister? If we're discussing historical katanas, it's worth noting that these swords were crafted for both practical and aesthetic purposes, and the idea of one being inherently "evil" is subjective and open to interpretation. Alternatively, if you're referring to a fictional katana, could you provide more context or details about the weapon in question? It's difficult to give a definitive answer without knowing the specific context or criteria being used to determine what constitutes an "evil" katana.