Ragna Crimson takes place in a world where dragons are known to be humanity's natural enemies. There are two effective ways to kill them: freezing their blood with silverine, a trait found in silver weapons, or exposing them to sunlight. Leonica, a skilled young hunter, partners with her friend Ragna, who lacks the typical skills of their profession and is even shunned by some due to a perceived curse. Ragna is convinced Leonica is immune to his bad luck, but his confidence is shaken when he has a vision of her death.