From the creator of Onegai Sensei, this is a story about a beautiful alien who landed in some rural area in Japan and the local high school kids that she interacts with. Sounds familiar?! Of course it is! It builds on the same premise as Onegai Sensei, and it even uses the same set of characters! (Although the sensei is now senpai hehe)
But be that as it may, I like this series better than Onegai Sensei. It's more lighthearted and more heartwarming. It doesn't have the teacher fetish. Although they still co-habit due to circumstances (like a boarder), it is played down in this series and is known by their friends so the humor, or rather, the funny circumstances, does not revolve around the nobody-should-know-we're-living-together hide and seek situation like in Onegai Sensei. Also, it does not have that medical drama condition the protagonist is suffering from, the closest relation would be the accidents that the main character gets into this series.