Fifteen-year-old Sei Saotome is the type of person who tends to fail at the most crucial times. After nearly becoming a high school drop-out, she enrolls into a school that is overambitious for her. There she meets the bold and popular Taiyou Udagawa; and the dreamy and stars obsessed, Mizuki Ootaka. After being asked by Mizuki to join the two guys in the Astronomy Club, it turns out high school life isn't as bad as she had expected.
Miyu and Shuya are high school students. They have dated for 2 years. Miyu and Shuya have a promise that no matter what, they will watch a movie together on the first day of each new month. When Miyu and Shuya are on their way to the movie theater, Shuya suddenly cancels their date. Shuya seems like he is hiding something and he acts nervous. Later, Miyu goes to the place where she is supposed to meet Shuya, but she witnesses Shuya getting into a car accident. She panics, but when she wakes up she finds herself on the morning of the accident. Miyu keeps waking up on the day when Shuya got into an accident.