Kusanagi Kei, a high-school student living with his aunt and uncle, has an encounter with a female alien. This alien is revealed to be a new teacher at his school. Later, he is forced to marry this alien to preserve her secrets. From there, various romantically-inclined problems crop up repeatedly.
Unlike negative reviewer(s), I found the Onegai Teacher manga absolutely fantastic. So great that I gave it, as you may or may not have noticed a 10/10 rating. For me the only other manga that accomplished this high rating was Air Gear, which has pretty much everything needed for a Shounen genred fan like me. So why did Onegai Teacher have such an impact on me when it's not even shounen? Well, here are the reasons, you don't have to believe me, but please do give a try to the manga and check it out.
I'll start with some background on myself, in accordance to
anime/manga: I like watching and lately, since 2008 reading those which have or are dramatic, particularly hentai manga's. The slow progressive start of the plot to the climax, and then the finale. This has to be very clear and thorough. Onegai Teacher manages to show it in manga form. The manga may not have various scenes provided in the anime, such as the beach arc and the parts which include the male Sensei (the guy who likes planes), but it surely doesn't lack nor stop to accomplish the drama which it intended to show and gain support of from the fans. And unlike the anime, it doesn't end in cliffhangers, as far as I can remember.
It doesn't stop there, there are other aspects which to me are better than the anime, it's supposedly based from. For example, puns. For someone who understands verbal Japanese quite well, especially when it comes to puns, the anime fell dearly short, the acting was weak, and when you would think they would put it up a notch, it failed. In the manga, however, those puns are clear and quite entertaining. My only disappointment if I had to say would be the lack of "echii-ness or nudity (like the anime ova)," although the drama does back that enough to not think about it. In the end, I nearly came to cry because of the way it ended, and probably would have if I was listening to a depressing tune of something. I would wish anime and manga companies make more dramatic stories like this, especially dealing with teacher/mother and son/student scenarios.
In short, taking MAL's system to mind, perfect for the story, perfect for characters, perfect for enjoyment, art could have been a little better, but for it's time it was the average, I guess. Overall? I stand by what I mentioned at the beginning.
I hate to say, but the Onegai Teacher manga was a huge disappointment. Unlike most cases, the manga was based on the original anime and in my opinion they did not do a very good job on the adaptation. Many elements of the anime are missing (for example the character of Hatusho has practically no part in the manga) and there were significant changes in the storyline, all of which made the whole thing weaker.
My advice is to just stick with the anime, and give the manga a pass.