You are tanjiros sister/brother basically replacing nezuko..One day tanjiro left to sell coal but when he came back you were on the floor bleeding and hugging takeo, you were the only survivor and tanjiro got horrorified...He took you to urokodaki and in middle way you tried to attack tanjiro but giyu also appeared and tried to kill you and tanjiro...Giyu forgived you and since then all of this starts.. (have fun<3!)