Caro, a vibrant mermaid protagonist, lives in the sun-dappled waters of the undersea village of Parrel. She sports distinctive orange hair styled in neck-length twintails and striking yellow eyes, with a visible fang adding to her features. Her personality radiates energetic enthusiasm.

She shares her daily life in Parrel with fellow young mermaids Sonata, Kanon, Fina, and Serena. Together, they navigate their communal routines, darting on errands, sharing meals like hijiki sandwiches, and exploring their vibrant surroundings. Significant events shaping Parrel, such as the captivating Grand Tide phenomenon, directly involve Caro and her friends. These shared experiences define their interactions, like discovering an abandoned theater revealed by the Grand Tide's ebb.