Fifteen-year-old Nonozumi Kanata has held a flame for a boy named Haruka ever since they met on a family holiday nine years earlier. That summer, Haruka became Kanata's first kiss, and the memory of him has stayed with her ever since. All she has left of that encounter is a single photograph of the two of them together, which she carries everywhere as a treasured keepsake. When Kanata realizes she will be spending the summer vacation alone, she decides on a bold plan: to track down Haruka using only the address written on the back of the photograph as her clue. Unfortunately, Kanata is hopeless when it comes to travel, and she nearly boards the wrong train at the station. At that moment, she is rescued by Kasukabe Kairi, an extremely handsome and popular boy from the other class at her school. Kairi happens to be heading in the same direction and offers to guide her. As they journey together, Kanata opens up about her search for Haruka and the dream that has driven her all these years. Kairi is drawn in by her sincerity and decides to help her. The path takes them to Haruka's hometown, but the reunion may not unfold exactly as Kanata has imagined. Along the way, Kairi's protective and caring presence begins to stir feelings that complicate her long-standing devotion to a memory. The story explores the collision between a childhood ideal and the growing reality of a new connection, set against the backdrop of a single eventful summer journey.