A happy dog lives a peaceful life with his beloved old master, always looking forward to his next meal. Outside their home stands a giant, ancient tree where mysterious wood spirits dwell, appearing only when the wind whispers. One day, a spirit summons a torrential rain that floods the entire town, sweeping the dog and a young boy out to the vast, open sea. Drifting on nothing but a small doghouse, the unlikely pair faces mysterious deserted islands and encounters strange, unknown monsters. Will they ever find their way back home to the old man? An extraordinary adventure begins.