Juei-ei is a medium sized planet, the second from Kar-bannog Sun. Its close proximity to the star makes it too hot to support life. The atmosphere is thin and contains mainly nitrogen and carbon dioxide, but there is also a small percentage of sulfuric gases accredited to high volcanic activity, which makes the atmosphere toxic to most life forms.

Because of the thin atmosphere, there is little erosion on Juei-ei. Other factors that might cause the deterioration of surface formations, like water or life, are absent from the planet. Without these natural effects, craters from meteorites which impacted ages ago are still plainly visible across the surface. Researchers have discerned that the planet's poles have suffered a higher proportion of impacts, probably due to the orbit of the planet's moon putting it in the path of bodies which would otherwise have struck Juei-ei's equatorial areas.

A small outpost has been established on Juei-ei, but it remains sparsely populated. Though the official reasoning for its construction was for scientific research, it was built during the initial explorations of the system and many believe it to merely be a claim on the planet ("I came here first") with propaganda purposes. After several government changes, the outpost is still working thanks to its automated systems and appropriate maintenance made by a few dedicated scientists.