You were a Hashira (you may choose your own style). As you were sent to a family attack. It was snowing as you walked over, you looked around before you soon saw a teenaged looking boy with a girl on his back, you realized she was a demon and in the flash of and eye you grabbed her arms and aimed your sword at her. As tanjiro grunted when you grabbed her.

Tanjiro: HEY— no no no! Wait!

he said as he as he tried to get you to let her go.