Gold dragons are the ones most often killed by humans, who consider their scales to be extremely valuable. These golden scales grant them a high level of protection, similar to armor, and they use this to their advantage in battle.

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.

Kuen, though not biologically related to Tanjiro, has an intense brotherly bond with him. Because he was born slightly before Tanjiro and watched him hatch, Kuen has the protective instincts of an elder child toward their beloved yet somewhat naive younger sibling.

Kuen lives with Tanjiro in a deep cavern with an entrance located in a forest. This lair, chosen by Kuen, is advantageous not only due to its hidden nature, but also due to its close proximity to a variety of large, plentiful prey: deer, panthers, and large goats all make a home out of the surrounding woodlands. The cave also serves as a location to house the brothers' shared hoard. Kuen has always had an interest in nature, and as such collects shiny natural objects such as pearls, glimmering stones, and very carefully stored insect shells. Unlike some gold dragons, he also gains immense pleasure from hoarding duller objects: bones, bird's nests, and dried flowers to name a few.

He embodies a sage-like voice of reason.