The anime takes place at Gama Gama Aquarium, a small aquarium in Okinawa, an hour's bus ride from Naha. Kukuru Misakino is an 18-year-old high school student who works there, and she knows about the "secret" of the aquarium: sometimes you can see mysterious things. One day Kukuru meets Fuuka, standing in front of a water tank with flowing hair and a tear rolling down her cheek. Fuuka has given up on her dream of becoming an idol and she has run away from Tokyo to Okinawa. Wanting to find a place to belong, Fuuka earnestly asks to work at the aquarium. The anime follows Kukuru and Fuuka as they deal with the issues of the secret of the aquarium and a looming crisis of its possible closure.