Swallowtail Dragons are graceful and quick flyers, much like their namesake bird. They are capable of precise aerial acrobatics, and can reach very high altitudes. Because of this, humans observing these dragons are often astonished at how large they are when confronted up close. A Swallowtail’s diet consists of insects and small mammals plentiful in temperate forests. These dragons are also made remarkable by their paper-thin wing membranes, which allow light to pass through, creating an astonishing effect on starry nights.

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.

By coincidence, all of the humans who have seen Tsubamechi have had a bout of good luck shortly after the sighting, earning her the nickname "the Swallow of Fortune". While she had nothing to do with the luck that she brought (which usually involve financial or marital success), many human merchants seem to think otherwise and have gone to great lengths to try to find her. Being rather shy, Tsubamechi is rarely seen near human habitation, and her preference of high altitudes make her even more elusive to the common merchant. This has turned her into nothing short of a legend and many unfortunate Swallowtail dragons have been caught and caged in hopes of capturing the mysterious "Swallow of Fortune". It is believed that Tsubamechi herself has yet to be caught.