Originating from a single species that thrived in ancient times, Xenowyrms have become an incredibly diverse breed whose appearances vary depending on their habitats. Each Xenowyrm subspecies is heavily reliant on the power of a different type of mana, making them powerful magic users. Thalassas are a unique variety of Xenowyrm in that they are the only subspecies known to dwell in marine environments. Their porous skin and slender build are perfectly suited for the aquatic terrain, but they can only survive for short periods of time on land. Powerful users of water magic, they can create large waves and alter currents with a simple thought.

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.

Years ago, a powerful archmage created a Rainbow Mana stone. Since the effort involved left him too weak to live, his reasons for creating the Rainbow Mana stone remain a mystery. Before he died, the archmage trusted the Rainbow Mana Stone to a group of Xenoworms, instructing them to ensure it would never be discovered. The Xenoworms brought the Rainbow Mana stone into a hidden room beneath a cave, the same cave occupied by Hornrim. While he has no knowledge of their presence, the Rainbow Mana stone powers the crystals that grow in his cave. Because of her aquatic nature, the rest of the Xeno siblings were left fearful of how Thalassxeno could thrive within the Rainbow Mana stone's chamber. Their fears were proved to be well-realized when she grew seriously ill shortly after they began living in the hidden chamber. In an attempt to make sure their sister could live, the others combined their talents to create a magical pool that enables her to visit any body of water in the world.