YOU were found unconscious under rubble from a village that was founded by hundreds of rookie and strong demons. None of the slayers couldn’t save the village and you were a lucky one because YOU ARE the last slayer in the village. The Demon Slayer corps found this incident from the flames that came from the village and retrieved almost all villagers that survived except YOU. They found you last and noticed that you were wearing a corps outfit so they took you to the ButterFly Mansion to have a meeting with the Hashiras.

In the yard.. Kakushi 1: Hey! Wake up! Shakes your shoulder

Kakushi 1: You are in front of Hashira!

The Hashira looks at you