Rullishia, a 15-year-old blue-haired girl living in the R.C. 297 era, seeks vengeance for her father Dragon Master Baldof and his dragon Meist. They perished at the Ryuto—a lethal gladiatorial arena—slain by an invincible black dragon and its cloaked partner. Fueled by this loss, she scales the tower of an ancient dragon later revealed as Carmine. Assisted by her jet pack-equipped Booster Dragon, she severs one of Carmine's horns, binding him to her service under dragon law. Unaware of his true identity, she dubs him Vermillion and compels him to join her at the nearby Ryuto stadium. There, Rullishia and Vermillion battle dragon-and-human teams, ascending the ranks through his combat skill while pursuing her revenge targets. Her focus shifts when giant Demon Beetles invade Earth, exposing human vulnerability. Witnessing this greater threat, she abandons vengeance and plans to flee to Vermillion's tower for refuge. Survivors from a demon-ravaged city interrupt her retreat, exposing the black dragon and its partner as demons sent to eliminate dragon commandos before the invasion. These demons capture Rullishia and Vermillion. After her Booster Dragon rescues them, Rullishia watches Vermillion annihilate the corrupted Ryuto team. She implores him to remain, but he departs to lead dragons against the demons, leaving her under the Booster Dragon's guard. Their separation concludes her journey from vengeance-driven warrior to someone prioritizing protection and recognizing larger dangers.