Thunder Dragons are the masters of electricity. Their wings gather energy as they soar through the clouds, and when they clap their wings together they can create devastating arcs of lightning. They can stay airborne nearly indefinitely, landing only to sleep and breed; they catch their prey from the air and take moisture from the clouds. A thunder dragon’s roar is considered to be an omen of misfortune.

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.

During the war of the Iron roar Clan and Black Flame Clan, several Iron Roar dragons ventured to the desert to recruit eggs, little they did know that they will encounter a legendary thunder egg that is Desseriu; he is first of all the elemental-related dragons of the Iron Roar to fully mastered the element of electricity, even surpassing the Elite General Kuryentei, thus giving him the honor title "Master". Desseriu is calmed and collected at all times, he rarely express his anger, and he got many friends due to his popularity and he got very few true friends due to his caring nature.