The protagonist, Itsuki Kusumegi, has a fiancée whose face and name he doesn’t know. His 17th birthday, when he will find out who his fiancée is, is just about a month away. One day, Ikki meets Sae Sumiya, who attends the same high school, and for the first time experiences the feeling of falling in love. His childhood friend Nene Amahane supports Ikki with all her might. It’s autumn, and Itsuki’s peaceful high school life is slowly beginning to change. With their respective intentions intersecting, how will the story of these three people end up…?