Dragons are creatures with nearly unlimited life spans. They can survive for long periods of time, and no one has found a dragon that has died of old age. Adolescence 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. Once they hit adolescence, hatchlings change quickly, maturing to their full forms in only 2 years.

Dragons don't communicate with each other verbally, but they will growl to scare off predators and frighten prey. Young dragons will emit an extremely high-pitched squeal when they are frightened. To communicate, they use telepathy with each other and to speak to other creatures.

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.

Kurokusuru Hitotsu is the leader of the friendly four club of dragons. The friendly four as they are known when seen together are a group of dragons dedicated to making the world a better place starting with their clan. Kurokusuru Hitotsu being the leader has the privilege and obligation as leader to decide what they are going to do to make the world and their clan a better place. It is not a privilege he takes lightly. Therefore he is a bit of a stick in the mud when it comes to doing something fun. Nevertheless he is the leader and they couldn't do without him.