manga of the series is a prequel that takes place a century ago when humans were forced to live undersea when the cities were Greek named. Elpida means "hope." Now they're Russian inspired, like Kamchatka. Ai Mayuzumi, Millie's great grandmother is the protagonist of the story. Characters Maia is the protagonist of the series. She has lost all of her childhood memories, because as a child, Maia was put into a one year coma because of a car wreck. The cause of it was because while in the car with her parents, the controls malfunctioned. Her parents died. Waking up, she was introduced to a man claiming to be her grandfather. In episode 11, Maia tells the girls of Nereids her story of waking up from her coma. During the flashback, Maia asks her grandpa why whenever he smiles at her, he seems sad. At the end of the episode, she is looking at a picture of her grandfather then she asks, "What is it that you were keeping hidden from me, Grandpa." Although Maia is an excellent student she is rejected by the Ocean Agency, an elite paramilitary organization that is part of the futuristic world government. So instead Maia, broke and homeless, joins Nereids, an unorthodox help-for-hire organization inspired by the Greek mythological Nereids. She is optimistic, hard working, and honest, yet a naive and shy cute girl-next-door. Maia is in search of her past and continues to do so while working with Nereids. Leader of the Nereids Kamchatka branch. Rena is capable, elegant, and cunning, although she can be cold at times. Although not the branch manager in title, she is the de facto leader and makes the decisions. She is cool and calculating and her sharp instincts enable her to know the weaknesses of other people. Rena has no moral qualms about seducing others for manipulation or for a weapon use. She is also frugal with money and deducts pay from salaries under even the slightest pretext. Busty and bespectacled with purple hair, Shizuka is a brilliant mechanic who grew up in an inner city district of Shibuya and knows many people there. She is known for her poor shooting aim and is friendly, casual, and trusting with a voracious appetite for food. Loud, spontaneous, tomboyish, and somewhat reckless with a ganguro style complexion, Gloria is a trigger-happy champion marksman and the weapons specialist with a