On the planet Aqua, a world once known as Mars, Akari Mizunashi has just recently made her home in the town of Neo-Venezia, a futuristic imitation of the ancient city of Venice. In pursuit of her dream to become an Undine—a gondolier who leads high-end tours around the city—Akari joins as a trainee with the Aria Company, one of the three most prestigious water-guide companies in Neo-Venezia. There, she spends her time practicing her rowing skills, learning more about her new home, and meeting all sorts of fun and interesting people along the way.

It's now been twelve months since Akari began her new life in Neo-Venezia. As the weather becomes colder and the seasons begin to change, she finds out there are so many new wonders to discover with each passing day on the incredible water planet, Aqua!