The Pinnacle of Swordsmanship Is Within Reach

"Are you a ghost?"

"I am... I killed people... a lot of people."

"Did you eat them all?"

"Eat people?... What kind of disgusting thing is that?"

"Looking at you, it's hard for me to believe what you're saying."

"Ever since my left arm mutated, no one has believed me."

"But I can't afford to die before I find the source of this curse, so... I'm sorry. After that, I'll let you kill me with your own hands."

This is a mutated Demon Slayer world.