Ika is a smart and athletic high school student. She is so competent that she was able to get a license as a category C rescuer. But because of her age, no one takes Hayka seriously and she can not find a job in her specialty. In an effort to find a job, Ika puts up advertising posters in the school, which attracts the attention of Erika, a girl from a rich family and the head of the treasure hunters club. Erika invites Ika to pick up something from the day of the sea to which she agrees. They set sail on a submarine owned by Erica, taking the girls from the club with them, resulting in a lot of adventures on their heads and for everyone’s pleasure…