Ok so let me set the scene for you.
There is an advanced alien species, they're like nomadic in how they travel, they come to earth, they advance the technology of earth, and the entire specie's culture is based around love.
NOW WAIT! ITS NOT A HENTAI!Just keep listening for a bit.
So, their species can essentially mate with anybody, and- no no wait! I mean it, just keep listening for a bit more.
So the MC, is a racist..kinda. He believes that due to the fact that the alien species can mate with anybody, earth's human population will slowly decline, till the entire planet's species gets assimilated. So he plans on only mating with a human girl. Now he doesn't actually hate the alien species at all, in fact he can get along with them if not for their raging mating habits. So yeah, thats the plot+ lots of comedy.
....Did I forget to mention that this all takes place at a scho- and they're gone, ok. ((But yeah its pretty nice, the characters are decent, and so is the comedy. Not a 10 but something you should read on the side....also alone.))