Stone Dragons have a tough outer covering made of a stone-like material. They eat rocks, using the minerals they contain for nourishment and to keep up their stone outer shell. They rarely move, and are the heaviest of all types of dragons. Although they have wings, indicating flight ability, no one has ever seen a stone dragon flying.

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.

Ookii Maruishi, as a Stone dragon, was named after the Japanese words meaning "Big Boulder." She was called that by the other dragons because she never moved, was made of rock, and never flies. It wasn't a name they were giving her however. It was an insult. She took on the name and tried to prove them false. Challenging Kitsui Shippo to a race, Ookii Maruishi was left in the dust. Since she lost but shown lots of courage, the other dragons seemed to accept her and Ookii Maruishi has become a loving member to the community. The only friend she really stays with and understands is Furuemasu Tsuchi.