What is Humanoid Alien manga?

Humanoids are aliens, intelligent beings who do not originate from Earth, but have a striking similarity to humans or at least show the basic body layout, i.e. two arms and legs, head with two eyes and ears, one nose and mouth. Though the latter - head-related features - may vary. As "DearS" shows some aliens actually exhibit super-human beauty, or as in the case of "Onegai Teacher" they are genetically compatible to humans for some strange reason.