Isamu is a small moon orbiting the planet Birjis, a bluish-purple gas giant, in the Birjis system of the Dalchon sector. Isamu, much like its larger sister moon Derora, is composed mainly of silicate rock which provides a stark contrast to the gas-based planet that it orbits. This contrast has resulted in a terrain of mountain ranges, valleys, and plains which are covered in several different types of forests.

While Isamu appears on detailed maps of the Birjis system, it is usually only mentioned as being a moon of the planet Birjis rather than being under a planetary body on its own. The moon doesn't have any specific natural wonders or been the site of noteworthy events for the wider galaxy to take much interest in it.

Not much is known of the ancient history of Isamu. Some scientists have theorized that Isamu may have initially started life as a dwarf planet orbiting the Birjis Sun but was pulled into its current orbit in the early formation of the star system. These scientists cite the slightly odd orbit of Isamu and lack of any silicate rock planets in a closer orbit to the Birjis Sun as evidence for this theory, though this concept is not universally accepted, and further research is required to either prove or disprove it.

Isamu is geologically stable despite its proximity to the planet Birjis, with what is considered a medium gravity environment for a moon of its size. It has an oxygen-rich atmosphere with a predictable climate cycle. Forests dominate the landscape ranging from woodlands to temperate deciduous forests, with boreal forests in some of the higher mountain regions. Although there are no saltwater oceans on the surface, there are several larger freshwater lakes fed by smaller rivers and streams.

While large wildlife is not overly abundant in the forests, many smaller creatures thrive. Quadrupeds of numerous varieties make homes in the trees feasting on fruits, nuts, and seeds. Flying creatures can also be seen flitting between the branches or heard occasionally as they burst into song. Some imported species such as quizzers, boma beasts, and eye-snatchers have also successfully made the forests of Isamu home. Similarly, the river systems and lakes support several varieties of freshwater mollusks, crustaceans, and fish species.