Based on the manga by Kitagawa Shou, which ran for 15 volumes in "Young Jump" magazine starting 1990. At the time of the ceremony of entry to the college, a young boy named Ushino Hayama finds Sara a girl whom he met ten years ago. From this day, a change has taken place in him, and notices that can now control some water. After having succeeded the swimming championships, he discovers deep sea diving. (Plot summary taken from AnimeNewsNetwork)