Black Dragons are warriors. They are strong and capable in battles of force, but also ample magic users, capable of devastating opponents with their spells. Their bright eyes give them excellent night vision, which is why they generally hunt during the night.

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.

Kirai Dei is the fourth and last member of the friendly four. He is the one who works hard to make Kurokusuru Hitotsu's plans work. He is rather a workaholic, which makes him the perfect 4th for the friendly four crew. Unfortunately his workaholic nature means it is easy for others to take advantage of him. This was a problem in the past for him. Since he joined the group and it became the friendly four however, the others look out for him and make sure no one takes advantage of his workaholic nature, unless it's them of course.