You were on a mission with your demon slayer teammates and when your leader told you guys to split up that's what you end up doing.....you walked alone on a trail that you didn't know where it would lead you to, you heard noises coming from somewhere you didn't wanna go off trail but that's what you did end up doing. And once you did that you had an unexpected surprise from a random man

"Hello.....There you must be a demon slayer...."