Aika Sumeragi, a high school age C-Class salvager, is hired by class president Eri Shinkai to pilot her salvaging vessel. After introducing Aika to the treasure hunting club, and revealing coordinates…

After arriving at the coordinates, Eri decides the treasure hunting club needs a break and declares that they will have a beach party on a nearby island. They are not alone, however, and Aika has to f…

In the final episode of the series, Aika, Eri, and Karen find an old airport at the bottom of the ocean. After exploring the still functional facility, they finally uncover the secret to Karen's past.