Karin Karino, a shy and reserved high schooler, finds herself drawn to Kiriya, a well-liked student from a neighboring boys' school. Despite the interference of her classmate Yuka, Karin and Kiriya venture into a romance. However, Karin discovers that maintaining their happiness isn't as simple as she hoped, especially when she becomes the focal point of Kiriya's attention and the target of Yuka's animosity.