Akari Mizunashi is the central protagonist of her story, a fifteen-year-old girl who immigrates from Manhome, the planet formerly known as Earth, to the terraformed world of Aqua, once Mars, with the dream of becoming an Undine, a professional gondolier and tour guide in the replica city of Neo-Venezia. She is employed by the Aria Company, where she lives and trains under the tutelage of the renowned Alicia Florence. Akari has pink hair and green eyes, with long locks on the sides of her head often bound by yellow clasps, a feature that leads to her being playfully nicknamed Momiko, or Sideburns. Her birthday is January 30th, and her height is recorded as 155 centimeters. Her personality is defined by an unwavering and cheerful optimism, a deep appreciation for finding beauty in mundane or overlooked aspects of daily life, a quality her friends call the Akari filter. She is pure, innocent, and speaks her feelings openly, often exclaiming her delight with phrases like Ah, suteki, and using soft exclamations such as Hahi and Hohe. Her primary motivation is her love for Neo-Venezia and her desire to become a fully-fledged Prima Undine, a goal she achieves after progressing from the rank of Pair to Single and finally passing her promotion test, earning the professional title Aquamarine, also known as Distant Blue. Throughout her journey, she forms close friendships with fellow apprentices Aika S. Granzchesta and Alice Carroll, shares a profound bond with her mentor Alicia, and later mentors a young girl named Ai as her own apprentice. Akari possesses a unique rowing style: due to a mistake made while practicing on a simulator back on Manhome, she learned to row backwards with unmatched speed and skill, though her forward rowing was initially slow. Beyond her physical abilities, her greatest talent is her extraordinary capacity to befriend nearly everyone she meets and her openness to the supernatural, which leads her to frequently encounter mystical entities such as the cat spirit Cait Sith. She eventually inherits the Aria Company and its gondola, growing into a capable Prima who carries forward the legacy of her teacher.