Royal Blue dragons are a nocturnal breed who prefer to live high in the mountains near slow-moving water that reflects the night sky. Although quite capable of defending themselves, they are peaceful by nature and will avoid a fight whenever possible.

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.

Tsukihoshi is a Royal Blue Dragon and is an enemy to Flame-Hound the Royal Red Dragon. She is very calm and reassuring most of the time, but when she's angry she can cause an uproar loud enough to awaken the dead. She is friends with Touketsuishi and Guardian-Winds, and she babysits their child often along with the other hatchlings.