Akari Mizunashi, at the age of 15, has left everything behind to travel to Aqua, a sparkling planet covered in water. 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?

One morning, Akari wakes up to find the entire city flooded with water! It's the Acqua Alta, a once-a-year phenomenon where the water levels rise, causing all of Neo-Venezia to shut down for a day. But while most people spend the day relaxing, Aika's mentor Akira is as strict as ever, and yells at her to get back to training. Aika has just the solution to get her mentor off her back: she's running away to the Aria Company!

While training in a particularly tough stretch of water, Akari and Aika meet girl from Orange Planet who seems to be having no trouble at all. Her name is Alice, and she's famous for being one of the youngest yet most talented Undines in Neo Venezia. There's just one problem... she never seems to smile. What could she learn from a day spent with the unlikely pair of Akari and Akatsuki?

Akari and President Aria are wandering through the marketplace one evening, when President Aria suddenly leads Akari to a plaza she's never seen before. There, a little girl with a bell around her neck gives Akari a letter, and asks her to deliver it. It seems very important. But if Akari's going to have any chance of keeping her promise, she'll have to enlist the help of flying messengers known as Sylphs!

When Akari was little, she was certain that Neverland was a real place. As she grew up, she understood that it was fantasy... But now, she's received a mysterious, hand-written invitation to visit Neverland for herself! What awaits her as she follows her map toward a quiet, deserted island?

Alice is in a pretty bad mood. Her dorm doesn't allow pets but she's secretly taking care of a kitten; her mentor Athena is an absolute clutz; and to top it all off, she has decided that her left hand isn't as skilled as her right hand, and is therefore useless. Though Alice certainly does have a strange set of problems, and they all seem separate from each other, she's certain to discover that the answers to each all are connected.

Akari, Aika and Alice are scheduled for a full day of training with Akira, and what's more, two customers will be along for the ride. They're a couple on their honeymoon; but while the wife loves Undines and riding on gondolas, the husband thinks being an Undine is simple work, and couldn't really care less about the whole thing. It's up to Akira to teach everyone what it means to be an Undine - Undines-in-training included!

It's a double dose of President Aria! In "That Melancholy President...", it's cleaning time for the Aria Company, and President Aria wants to help out and lead by example for his company. Yet he can't seem to do anything right, and only gets in the way. He's so sad about it, that he's determined to run away... but where will he go? And in "That Cool Hero...", we get to see President Aria's cute crime-fighting alter-ego: Nyan-Nyan-Puu!

Fall has arrived in Neo-Venezia and the girls have switched into their winter uniforms. And yet, Aika feels so unmotivated... She wants to do more than just go through the motions of everyday practice. She wants to really sharpen her skills, and become as good as the legendary Great Water Fairy, the greatest Undine of all time! So the three of them are sent to go visit this legendary lady in her house out in the country... but she's nothing like what the girls expect.

Winter has come - the mornings are crisp and cold, and it's hard to get out from under the covers to go practice sculling. So as a special treat, Alicia suggests that they visit a hot spring! Akari's never seen one before so she's excited to go, and all the others decide to join in as well.

On one bleak winter day, when the clouds are thick and the snow is gently falling, the girls finish their sculling practice to find that Alicia, Aika and Athena are all together at the Aria Company, sitting around the fire. Over cups of hot cocoa, they discuss their younger days, and how it was that they all came to be friends.

Aria Company has no bookings on a snowy day, so Akari and President Aria visit the oldest bridge in Neo-Venezia. When they reach the other side of the decrepit covered bridge, the snow is gone, and the women she meets on the other side has no idea what an undine is. Together they wait for the terraformers to send water under the bridge for the first time.

It's time to ring in the new year, and everyone in Neo-Venezia has come together to celebrate! Even little Ai has come back from Manhome to take part in the winter festival. But as people gather and memories are shared, President Aria suddenly wanders off. Akari and Ai attempt to track him down, but what they find is a mysterious New Year's gift from Aqua itself.

As winter melts into spring, Akari, Aika and Alice all continue to practice and set new goals for themselves. But Akari still feels like she isn't good enough to become a Prima. Will she or any of the girls ever be truly satisfied with their talents?

Someone has requested Akari for a gondola tour! An old woman with a kind smile says that she'd like to see a side of Neo-Venezia that only Akari can show her. Akari takes her to many unique spots, but the woman already seems familiar with them all...

A new vendor has opened up shop in Piazza San Marco, selling heart-shaped chocolates in glass bottles. Akari buys a bottle, and later goes to buy another, but by then, the patissier has mysteriously disappeared. Where did he go, and will he ever return?

Akari wants to help out more around the Aria Company, but she's only a Single. So Alicia suggests she try her hand at working on a Traghetto! A Traghetto is a ferry-style gondola run exclusively by Singles. Will Akari be up to the challenge?

Athena and Alicia both have wonderful talents, but what about Akira? For that matter, what about Aika? Aika gets discouraged, thinking that maybe she doesn't have any natural talent, but Akira has an old story to tell that might lift Aika's spirits.

Akari can be a bit clumsy and makes plenty of mistakes, but it seems like Alicia never gets angry with her. Alice makes it her mission to see how Alicia handles Akari's faults, and to see if it's true that no matter what, she never scolds Akari.

Akari and Alicia are going to visit Anna, the woman who trained with Alicia in the early days of the Aria Company! Many memories will be shared on this visit, including how the Aria Company itself was first founded.

Alice and Athena are going on a picnic! Alice chooses a date and makes all sorts of elaborate plans... but Athena gets overloaded with work, and can't come. Athena tries to chase after Alice to apologize, but trips and falls - and somehow loses her memory!

Alice has just graduated from middle school. She feels confident, and excited about what's to come. And then, Athena suggests that they finally go on the picnic that they've been planning for so long. Alice's world is about to change...

Akari, Aika and Alice decide to partake in an old Manhome tradition, Moon-watching. Aika secretly invited Al to their get-together, but he hasn't shown up yet. Aika goes to look for him, but she has no idea what surprises the night has in store.

Alice is so busy now; every waking moment is full of appointments and work. Though she enjoys the life she has now, she still misses the time that she spent with her friends. It's starting to feel like she might never see Akari and Aika again.

As Akari and Aika leave for practice one cold winter morning, Aika has something to tell Akari. The two of them can't practice together anymore... As if that shock weren't enough, Alicia has something important to say as well.

Over the years, the Aria Company has changed. First it was Grandma's Aria Company, then it was Alicia's, and someday, it will be Akari's Aria Company. But that day might come sooner than Akari expected. Will she be ready for the future that lies ahead?