Kei is an 18 year old that has a problem. Sometimes he has this problem that he will black out for short and this one time long period of time. Kei is pretty much trapped for the time being in a body that is 3 years behind due to a black out that he had and he didnt wake up for 3 years. One day while laying down in the grass outside he encounters an space ship from outer space whos pilot was this beautiful woman. Next day it turns out this woman from the day before is his teacher, sent by her higher ups to watch over the education in earth. The Students, and faculty start to notice them being together and so that she can continue her mission kei and her marry so that there wouldnt be any problem with them being together. During the anime you get to see how their love for each other grows and what they do despite the obvious age difference.