What constitutes an alien creature or Starry Sky Great Demon?
As long as it is a demon beast that does not belong to the Lower World, it is an alien creature. An alien creature that can leave the Unstable Star Realm is considered a Starry Sky Great Demon.
Compared to the Alien Demon Beast, the powerhouses of the Seven Great Star Systems Alliance can still tame them. But alien creatures are different; they inherently do not belong to the Lower World and certainly cannot come from the Upper World. So far, even if alliance technology is advanced, it cannot detect which world the other end of the Abyss One Rift leads to.
Every space rift that appears in the Unstable Star Realm seems to have its other end reach a separate world plane.
Their appearance poses catastrophic challenges to the Basic Star Realm, Intermediate Star Realm, and even Advanced Star Realm that belong to the Lower World range.
