A high school student serving as the acting director of the small Gama Gama Aquarium in Okinawa. She has a straightforward and bright personality. Her passion for the aquarium is stronger than anyone's, and she shows a professional side that doesn't hesitate to use a harsh tone when living creatures are involved. She is out of touch with trends and fashion typical for her age. She is sprinting to revitalize Gama Gama Aquarium, which is on the verge of closing.

A former idol. After giving up on her dreams, she was drawn by a tourism poster she saw on her way back home and traveled to Okinawa, where she met Kukuru. She is serious, hardworking, and diligent. She is sensitive to the feelings of others and well-liked, but because of this, she sometimes struggles to express her true feelings. She works at Gama Gama Aquarium while living as a houseguest at Kukuru's home.

Kukuru's classmate and childhood friend. Before dawn, he boards a boat to help his father, who is a fisherman, and brings fish he caught himself to the Misakino household. He is a good confidant to Kukuru and volunteers to help with work at Gama Gama Aquarium during summer vacation. He's a good guy who uses proper polite speech with his elders. He has a secret crush on Kukuru.

A keeper at Gama Gama Aquarium. He is blunt and seems unmotivated, but he does his job thoroughly. He is actually uncomfortable around women, to the point where he avoids eye contact even while speaking. Due to a shortage of keepers, his shifts are grueling, and he's always tired. He loves the homemade plum wine made by Kukuru's grandmother. He is the oldest among the staff and is called "Kuya-san" by everyone. He speaks with a casual-polite drawl to elders and normally to those younger than him.

A civil servant working for the town's tourism association. She is a reliable older sister figure who helps with aquarium work and actively provides support whenever there's trouble; to Kukuru and the others, she's like an "older friend." She is the same age as Kuya and went to the same high school, but they have a bit of a cat-and-dog relationship.

Kukuru's classmate and friend since elementary school. She is the poster girl who helps out at "Kamee," the diner her mother runs, where the group often gathers. Her nickname is "Udon-chan," a play on her name Tsukimi. She has a high-spirited and easygoing personality, but she is also caring and well-liked by everyone.

Kukuru's grandfather and the director of Gama Gama Aquarium. During summer vacation, he leaves the aquarium's operations to Kukuru and travels around for an "important mission" for Gama Gama. He has a very kind and gentle personality.