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 theirs fangs and injecting a venom that kills the baby inside.

Chidaruma is the elder Twin, and identical to her sister in almost every way. She and Chikemuri are never seen apart from one another, and it has become something of an urban legend for the hatchlings in the nursery that they are really the same being, just with two bodies... both of whom hunger for the delicious blood coursing through the veins of any hatchlings foolish enough to wander off past dark. At that point, the Twins have a habit of coming out of seemingly nowhere to terrify the hatchlings out of what little wits they possessed and send them screaming to the nearest non-Halloween adult. When the hatchlings manage to convince the adults to come back with them, however, Chidaruma and Chikemuri are long gone... and occasionally, so is an egg.