The plot takes place in an apocalyptic-like setting in Hokkaido of A.D. 1990, where a series of murders take place and dragons suddenly begin appearing in the skies. The Japanese SDF begins shooting the dragons out of the sky, holding them responsible for the murders. Following that, a troubled young girl named Riko is suddenly entrusted with the care of a hatchling dragon naming it Carmine (for his red scales), hoping to raise him for destruction against the city and all humans and after Carmine's mother was killed as a hatching. But however, Riko learns there is more to the dragons than she first learned.
Carmine is now all grown up living in a tower, setting place over 300 years after the events of Riko's story. Taking place in R.C. 297, a young 15-year-old girl named Rullishia comes to attempt to steal his horn. She has managed to successfully put it off and Carmine has now become her master. They then go to a dragon tournament called the Ryuto (where dragons battle with one another). Carmine is given the name "Vermillion" by Rullshia as they win one victory after the next. His friendship and good times with Rulishia are unfortunately cut short when the return of the demons is made imminent in a premonition Carmine has. After an actual attack by Demon Beetles made on a human and a dragon settlement as well as the current area he and Rulishia are fighting in, Carmine departs to do battle against the demons as now a leader of the dragon warriors.