Live in the ocean, protect the ocean, transcend the ocean - that’s what it means to be a Blue Mermaid!

Due to a shift in the tectonic plates around 100 years ago, much of Japan’s land was lost to flooding. In order to protect the remaining soil, cities were built one after the other across the water’s surface. Following the increase of water routes connecting these seaborne cities, much manpower became necessary in order to keep the waters safe.

Following this, women too began to advance into the ocean as professional protectors of the water. These “Blue Mermaids” soon became idolised by girls the nation over.

It is in this age that childhood friends Akeno Misaki and Moeka China, and their other friends who are aiming to become Blue Mermaids, enter Yokosuka Ocean Academy and start their bright and fun-filled (?) high school life!