Vampire Dragons are members of the undead. They sustain themselves by drinking the blood of others. It is said that they are only “alive” at night, and seem dead or asleep during the day, as they cannot endure sunlight for long periods of time. Vampire Dragons can only reproduce by changing the eggs of other dragons, puncturing the shell with their fangs and injecting venom that kills the baby inside.

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.

A rather amusing dragon for his species, Yami no Ou—whose name translates to "Lord of Darkness"—is a comical and somewhat perverted dragon who enjoys nothing more than causing havoc in the night. He sometimes sings an odd song when he isn't planning anything and in a good mood. Some people compare his nightly antics to that of the GGs clan during the day, minus the doodling along the sides of buildings. As a Vampire dragon, he tends to hide away in the deepest parts of the cave during the day, waiting for night to approach. How and when this dragon came into Kimoko's care is not entirely known, but there are many speculations, since neither of the two would ever say anything about the event that lead to the Vampire becoming a resident of Kimoko's cave.