Sei Saotome is a first grade high school student. She does not get along with the other students and her school life sucks in general. Things change when she meets male students Mizuki Otaka and Taiyo Udogawa. Mizuki doesn't talk much, but he likes astronomy. Taiyo has a sharp tongue and he is smart. They both plan to join the astronomy club which leads Sei to join the club as well.