Manga by author Mie

The world is being assimilated by a crazy religion, and to stop it I have become their satan. The religion is controlled by aliens, and people don't have a clue. The world says that aliens don't exist, but they are everywhere. How am so I certain? Because I am also an alien.

Third-year high school student Tachibana Kyou's world is shaken when a green-horned nurse suddenly arrives at his exclusively male school the doe-eyed, baby-faced, and irresistably adorable Hirota Natsu. Completely taken with the new faculty member, Kyou abandons his playboy lifestyle for her, having found true love for the first time But what will fate have in store for these two, engaged in the taboo relationship between teacher and pupil!?