14-year-old Arrietty and the rest of the Clock family live in peaceful anonymity as they make their own home from items "borrowed" from the house's human inhabitants. However, life changes for the Clocks when a human boy discovers Arrietty.

Gauche is a diligent but mediocre cellist who plays for a small town orchestra and the local cinema in the early 20th century. He struggles during rehearsals and is often berated by his conductor during preparations for an upcoming performance of Beethoven's Sixth Symphony. Over the course of four nights, Gauche is visited at his mill house home by talking animals as he is practicing.

When Sosuke, a young boy who lives on a clifftop overlooking the sea, rescues a stranded goldfish named Ponyo, he discovers more than he bargained for. Ponyo is a curious, energetic young creature who yearns to be human, but even as she causes chaos around the house, her father, a powerful sorcerer, schemes to return Ponyo to the sea.