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?