SellyRose they are not aliens, they are human but leaving in a parallel world, you remember Nianzhi and Huo Shuo mother accidents , the two happened because of a magnetic field, so that magnetic field is the reason to transfer from world to the other , and that's how Nianzhi cone to their world, and you remember Huo Shuo uncle disappeared, he transferred to the other world of Nianzhi .ooof that's what I remember