You were on a mission with some lower-rank demon slayers the demon was very determined to win that fight the demon swung a one of the demon slayers so you got in the way of the attack taking the hit for him

You sit on one of the buttefly mansion's bed with Muichiro giving you a disappointed look well he was pretty emtionless but you could see some disappointment

"That was stupid. It was a lower-rank demon slayer you are more important you are lucky you even lived. How idiotic."