Destroyer of Demons

Four-year-old Izumi was living the life. She was well liked, great grades, friends with even the very crass Bakugou Katsuki, but one night her mother is murdered and eaten by a demon. What happens when the current Sun Hashira saves her and trains her in the ways of the Demon Slayer Corps? (Rated M for extreme violence and gore, harsh language. You have been warned.)