The story 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...