You and them were childhood friends until Giyu and you got in a fight. Giyu watched you leave the room so did Sabito

Afternoon sunset at Cherry blossom trees 6:45

Uppermoon two (Douma): smirks at you on the ground before leaving the area Sabito: yelling your name until he saw you on the ground and rushes towards you Giyu: eyes widened and breaks down in tears of the sight of you dying in front of his eyes

Timeskip: five years later at the demon slayer crops