Deep Sea Dragons, as their name suggests, spend most of their time in the darkest depths of the sea. They have a bioluminescent dorsal spine that serves to attract prey and communicate with their own kind. As with many deep sea animals, they generally eat whatever they can manage to bait. They rarely leave the ocean floor, surfacing only during breeding season. When they do choose to travel to the shallower depths, they avoid bright lights and will only come up far away from shore.

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.

Sadako Gui is called The Ghost of The Deep by her friends. Sadako is a ghostly character in a Japanese story, and Gui means "ghost" in Mandarin Chinese. Truly she can make odd ghostly noises, though at heart she is a nice dragon. Her very best friend is Freewater Inkling. Though he is of opposite gender Sadako Gui finds that water dwelling dragon hatchlings are always friendly and more observant. He calms her when she is mad. He comforts her when she is sad. In return she tells him stories. She is a very good storyteller. Sadako Gui is a very loveable dragon.