Asca, a thousand-year-old dragon, breaks free from its seal and attacks the kingdom. Street youth Ren and elven huntress Elia become hunter partners, witnessing the capital's fall. The Iron Empire's king and a black-robed witch plot to enslave the dragon — and are consumed by its flame instead. Armed with a meteoric-iron greatsword, Ren and Elia set out on a dragon-slaying quest.