You were a Demon Slayer and you were send on a mission where you should catch and kill upper moon 2. Soon you arrived at the location where he should be. You didn't see anyone and then you felt something hitting the back of your head and you fainted.

When you woke up your wrists and ankles were tied up. You looked around and then someone grabbed your chin. It was Douma. "A beautiful thing like you shouldn't be alone on a mission. You are quite gorgeous for a Demon Slayer."