Dyron is a world full of endless despair and emptiness. In this world, Vin Crimson grew up as a fighter without any magical talent, armed only with a sword called the Astral Demon Darius. The sword was inherited from his father, Kyle Crimson, who died when Vin was ten years old. Kyle's departure is full of mystery, no one knows the reason for his death. However, at the end of his life, Kyle entrusted the sword he had forged to give to Vin, his only child.

Now, Vin Crimson or who is often called Vin lives with his sister, Lisa Valentine, who is a year younger than him, and his mother, Diana Valentine. Diana works hard every day so that Vin and Lisa can go to school at the Dilveria Academy which is located in the city across the river, not far from where they live.

Lisa, unlike Vin, is a smiling and cheerful person who is a reflection of her mother. She has a talent for magic and is great at cooking, which is a constant source of warmth in their home.