In a Japanese port town, a widowed father builds a machine to fulfil his late wife’s dream of a sushi shop in the city. His son Wataru, however, wants a different inheritance: the artisan craft of his grandfather, a master who knew every fish by name.
At a seaside shrine, the boy prays to become a craftsman like the old man. Diving beneath the waves, he finds his grandfather waiting — returned as a small red fish who still calls him by his nickname, “little sprout.” Together they descend through sunlit coral reefs and explore the sea; back in the kitchen, grandpa coaches the boy from a glass bowl as he learns to scale, fillet, and plate a meal. But Wataru’s obsession with a sushi contest draws him into dangerous waters, and the old man’s borrowed time is running out.
