One evening while watching the stars and contemplating life and the universe, Kusanagi Kei is surprised to see a UFO come down to Earth in his hometown, and a beautiful alien woman materialize before his eyes. He is even more shocked to find out the next day that the woman, Kazami Mizuho, is his new high school teacher! She realizes that he was the one from the night before, however, and makes him promise to keep her secret. Through a series of mishaps, Mizuho’s identity is almost given away, and Kei finds himself marrying her to keep her secret! Will Kei be able to learn to live with Mizuho and find love? Will he even be able to live a normal life?