Fuji, a novelist who loves rainy days, meets a slightly unusual 'dog' shivering in a cardboard box on a rainy day. Though it can't speak, this mysterious housemate communicates by writing on a flip board, and Fuji begins a slow, gentle life with it through the four seasons. This is the story of a warm, precious life shared by one person and one dog, who met on a rainy day. Based on Yuki Nikaidou's manga, which became a hit on social media, the anime began airing in July 2025.