Mayuki Munetani

She is the principal of Yokosuka Girls' Marine School and hails from the Soya family—a prestigious lineage of Blue Mermaids passed down through generations—and is the mother of Mashimo, Mafuyu, and Mashiro Soya.

Originally a member of the Blue Mermaids, she served as captain of the flagship Yamato nine years ago and was even slated to become the Director-General of the Maritime Safety Bureau; however, she chose to become an instructor at Yokosuka Girls' Marine School to dedicate herself to training the next generation. Amidst conflicts with the Maritime Safety Bureau, she prioritizes the protection of her students above all else.

During her active service fifteen years ago, she single-handedly wiped out an armed force through meticulous intelligence gathering and bold tactics, earning her the nickname "Tomoe Gozen of Kurushima"—a reputation that commands fear even now that she has retired from the front lines