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.
Ninako, who has an honest and gentle personality, lives her days without yet knowing the feeling of love. One day, she bumps into her classmate Ren on the train on her way home, and gradually becomes drawn to his hidden kindness. Ninako feels a pain, as if something has stabbed her in the chest. Eventually, she realizes that her feelings are "love," and she makes up her mind to tell Ren how she feels.
