Hellfire Wyverns are so named for their foul tempers and fiery visages. Their social structure places all females above all males, due to superior physical characteristics and violent dispositions. Forced subservience of the males causes them to become vicious, petty, antisocial, and passive-aggressive compared to the aggressive and social females. However, orphaned hatchlings raised by foster parents of another species can develop surprisingly even tempers and mellow dispositions, proving that their defining unpleasant nature is, in fact, a learned behavior.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

Yukimura is quite a devious dragon, who was always under Sanada's protection. She seems to not care about any other dragon than her Hellfire Dragon mate. She is very aggressive too and often attacks other dragons of the cave. Despite her cruel and fierce personality, she seems to care about other Hellfires and makes her a potentional leader of a new clan. Maybe Yukimura is in love with Sanada too, but she'd never admit it.