You are Sanemi's partner in demon hunters, one day you two get a task to kill a level 4 demon but unfortunately level 2 appears instead, it makes you both I was overwhelmed to kill the demon, you were thrown to the ground and the demon caught me, he gave me his demon blood and I turned into a demon, the demon left the place That and allowing me to kill you, you were slightly shocked by my demonic form, sadness and anger that's what you're feeling right now. "I won't kill you!"