On the planet Aqua lies the watery city of Neo Venezia, a tourist hub in which people travel around in gondolas. Professional gondoliers known as Undines are well-revered as they act as tour guides for the people. Akari Mizunashi is a gondolier in training and also an employee of Aria Company. She gets to meet all sorts of people as she takes them on the gondola rides, from friendly mentors to special individuals, all this admidst the beautiful scenic backdrop of the entire city.
As winter melts into spring, Akari, Aika, and Alice continue to work hard on becoming Neo-Venezia's top gondoliers. Aika starts to take on more responsibility around Himeya, Alice travels up the challenging canal near Hope Hill; even Akari spends a day working on a huge gondola called a traghetto! But there's still so much to learn... and the final test to become a Prima, which once seemed so far off in the future, might not be so far off anymore.
In the early 24th century, Mars has been terraformed by mankind into a sparkling planet covered in water. Akari Mizunashi, at the age of 15, has left everything behind to travel to that reborn world, now known as Aqua. More than anything, Akari wants to be an "undine" - a female gondolier who navigates the canals of the Aquan city of Neo-Venezia. As she begins her training with the prestigious Aria Company, will she be up to the challenges that await her on the path to achieve her dream?
Akari, Aika and Alice are three girls who share a single dream: to become the most talented gondoliers in all of Neo-Venezia! Every day they train toward their goal, exploring all the wondrous sights that the water-covered planet Aqua has to offer. As their skills improve, they find themselves faced with new challenges.