Set in near future, when many spacemen are seen everywhere on earth.
Common sense of the outer space is not effective on the earth.
It's been more than 10 years since the first contact.
Those spacemen who came in a group to the earth by a spaceship were just the same as humans living on earth, except that they can communicate freely using the antennas on their heads. Using their superb adaptability, they soon became accustomed to everyday life on the earth, and humans also accepted them as they are, before everyone was aware of it.
The strange daily life of MAYUKO, a serious-minded prep student, and NieA, a free and self-indulgent space girl, is going to develop.