After 150 years of terraforming, Aqua, the planet formerly known as Mars, now has over 90% of its surface now covered by water. A young girl named Akari Mizunashi arrives at the city of Neo-Venezia, an exact replica of the old Italian city of Venice, hoping to become an Undine, the most coveted job on Aqua. Follow Akari's adventures as she discovers the wonders of Aria in this prequel to the Aria anime and manga series.

Akari can now have passangers... as long as she is accompanied by Alicia. Despite failing her undine debut, she still manages to succeed, and even becomes closer to Presidente Aria. But when he feels unneeded and runs away from home, what will happen?

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 amidst the beautiful scenic backdrop of the entire city.

Akari is about to experience her first winter on Aqua with a new friend - a snow bug - and a trip to a hot spring. She also learns about Aqua's underground inhabitants and discovers the crucial role they play in maintaining the planet's gravity. And before she knows it, it's time for the Venetian New Year's festival, a celebration of magic, sparkle - and a carnival!

Spring has arrived on Aqua, marking a full year since Akari began her training. When the seasons change, it means it's time to race! There's a new trainee gondolier named Alice, whose natural talent is causing competition even amongst the most experienced undines, the Three Major Water Fairies. But will Akari's pure pleasure in rowing and springtime remind the rest that some races can also be fun?

Akari receives an invitation to the Neverland from Alicia. It turns out to be a surprise getaway, as Akarai has never swum in the true ocean. But in the sweltering heat, Akari sees a vision that will lead to an unexpected discovery.

Spring has come again and Akari now welcomes the start of her second year on Aqua. In the spirit of new beginnings, Akari sees a mysterious woman with a spectacular voice while helping the company president run some errands. Who is this person and what does she have to do with Alice? A fateful encounter, perhaps?