High School Fleet

A century after dramatic tectonic upheavals left much of Japan underwater, the country has reinvented itself around the sea. Coastal cities and vital shipping lanes are safeguarded by specialized naval vessels, and the prestigious “Blue Mermaids”—elite women dedicated to maritime defense—have become an aspirational path for many young students.

Childhood friends Akeno Misaki and Moeka China reunite at Yokosuka Girls’ Marine High School, where they train alongside classmates who share the same goal. As exercises begin, both are assigned command responsibilities, and Akeno settles into life as captain of the destroyer Harekaze, working to unite her crew. Their routine training takes a sudden turn when unexpected engine and navigation troubles leave the ship adrift, putting everyone aboard in immediate danger as they struggle to regain control and continue toward becoming full-fledged Blue Mermaids.