Mio Nagisa has a job as an oceanographer at the Shibaura University of Marine Science and Technology and has an interest in fish and also loves the sea. But she is reticent about her family and past life. Rintaro Hasuda is the second child of a wealthy family and comes back to Japan to look after his father's declining health and is put in charge of his father's marine development project. These two may come from different worlds but soon find that both have feelings for each other.