Boku to Uchu-jin

Manabu is a 3rd year middle schooler & former student council president. Suddenly he's in charge of a new student Ruri but she is no ordinary girl - she's an alien! Manabu loses the chance to be with his crush Mizuho who now has a thing for Ruri & gets nose bleeds from her cuteness. The teacher is of no help, her focus & nose bleeds are on Ruri's hot cousin who is also an alien!

Note: Chapters 1-500 are all covered in the serialized version of the series.