Daydream Dragons are the hosts of daydreams and fantasies. They spend the majority of their time sitting on clouds, dropping daydreams down into the minds of people passing by. Humans who live near Daydream Dragons must be especially careful not to let their thoughts wander, or they could end up spending hours or even days in a trance-like waking dream state.

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.

Miss Kairi Yumeji not only causes others around her to daydream, but she daydreams too. Her first name is from a character of a Japanese comic book known as Nightmare Inspector, whereas her last name means "to dream". Most of the time she is seen playing with clouds and giving people bizarre daydreams. In fact she is probably the leading cause of people tripping over little rocks in town.