**Height:** 155 cm Kei is living the life of a fifteen-year-old boy. He has a unique disease that causes his body to shut down into a death-like state whenever he becomes too stressed or depressed. He calls this a "standstill". The amount of time he remains in a standstill is random, usually lasting a few minutes to a few hours. However, one time, he went to a standstill and didn't come out for three years. So although everyone thinks he's 15, he is really 18. He discovers that his new teacher, Mizuho Kazami, is actually an alien whose mission is to observe Earth. Due to a big misunderstanding, Kei has to choose between letting her secret out or getting married to her.

Spoiler

At first, he is hesitant about the whole ordeal, but eventually, he falls in love and what ensues are comedic and dramatic situations which he must overcome to live a happy life with his new wife.