A young shark named Kozame lives in the nostalgic coastal town of Yauo Town, where even the simplest errand becomes a small adventure. Driven by curiosity, she explores her neighborhood, stopping to buy cider on a hot summer day, participate in morning radio calisthenics, or visit festival food stalls. Though her vocalizations are limited to enthusiastic gibberish, Kozame’s expressive nature allows her to connect with a variety of friends, including a frog named Kaeru-chan, a lizard named Tokage-chan, a monster called Kaijuu-san, and a friendly Shark Mask.

Each episode focuses on Kozame’s daily discoveries, from sharing frozen pops with friends to simply observing the world around her. The series embraces an episodic, slice-of-life format that highlights the warmth of community and the joy found in life’s quiet moments. As she navigates her seaside environment, the world sparkles when reflected through her innocent eyes, turning mundane outings into charming events.

The narrative later expands beyond Yauo Town. In a subsequent theatrical film titled Eiga Odekake Kozame Tokai no Otomodachi, Kozame travels to a bustling big city for a summer adventure. There, she encounters new characters, such as the shy Atlantic footballfish Anko-chan, the rabbit Usame-chan, and a salaryman named Haruto. While the original series focuses on the comfort of home, the film explores themes of meetings and partings as Kozame forms temporary bonds with city dwellers before ultimately returning to her familiar hometown as summer ends.