The story tells of Irihu Shuidou and Ayai Jienu, who were boyfriend and girlfriend in junior high school. They misunderstood each other over a small matter and broke up at graduation. However, the two of them who were promoted to high school became siblings due to their parents remarrying, and their memories of living together under the same roof made them unable to ignore each other's every move.
The story tells of Irihu Shuidou and Ayai Jienu, who were boyfriend and girlfriend in junior high school. They misunderstood each other over a small matter and broke up at graduation. However, the two of them who were promoted to high school became siblings due to their parents remarrying, and their memories of living together under the same roof made them unable to ignore each other's every move.