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.

Two wonderful things have happened: it's time for Neo-Venezia's annual Carnevale, and Ai has come back to Aqua for a visit! As Akari and Ai wander through streets full of bright colors and beautiful masks, they catch a glimpse of Casanova, the mysterious master of ceremonies. Who is the man behind the mask? The two are curious, but they'll need to be careful. You know what they say about curiosity and the cat, after all...

There's going to be a meteor shower, and Akari, Aika and Alice have made plans to watch it together. But this time, there's a little twist - Al, one of Neo-Venezia's gravity-controlling Gnomes, will be there as well. Even though he's shorter than the girls, he's actually three years their senior; and he knows all about physics, planets, and the beauty of the universe. What he doesn't seem to know, however, is how Aika feels whenever she's with him.

Akari and Alicia are visiting a shrine that looks just like the old Japanese shrines on Manhome. Though the grounds are beautiful, there's also a hint of mystery and danger in the air... Later, they are wandering on a different island, looking for a beautiful spot that Alicia once saw. But the farther they go, the less certain their path becomes. How do you reach your destination when you don't know the way there?

A short promo that aired after the first six episodes of Aria the Natural aired on AT-X.

While practicing one day, the girls see President Aria in his own little gondola. But he doesn't see them... instead, he disappears down a canal that's normally closed off. According to Alicia, there's an old legend on Manhome that tells of the Kingdom of Cats, a strange realm that people aren't allowed to enter. Could such a place really exist?

Akari is taking customers out for a tour! Alicia is along to help, of course, and it's a good thing she's there. When the tourists start asking questions that Akari doesn't know the answers to, Alicia answers them with ease... but this worries Akari. Will she ever know the city as well as Alicia? This sparks a fire in Aika and Alice as well - they've decided to compete to see which one of them knows the most hidden wonders in Neo-Venezia.

Akari has been given her very first solo job: carrying a shipment of Neo-Venezian glassware. They're beautiful pieces that sparkle in the sun, but the glassmaker's apprentice has a disposition that's anything but bright. He's sour and angry, and he's the one who'll be traveling with Akari as she delivers the shipment. Will Akari be able to handle the pressure of fragile cargo and a critical taskmaster?

Alice has created a new challenge for herself: when she walks home from school, she can only step on shadows. This is an ironclad law for her - but try as she might, she keeps failing. Even worse, Athena interferes by trying to help out. Alice's self-imposed challenge is something that she must conquer alone, or so she thinks; but maybe there's more to success than just doing everything by yourself.

Even though Akari is relatively new to Neo-Venezia, most of her friends have lived in the quiet island town all their lives. One sunny afternoon, as Akari, Akatsuki, Akria and Al are all eating lunch together, Al tells a story about when they were children, and the mysterious young boy who put Akatsuki squarely in his place.

On the night before her old gondola is set to be taken away, Akari and Alicia decide to have an evening picnic out on the water. As they laugh and talk, Alicia tells her stories of the gondola, and how it was an important part of her life as an apprentice, as well.

Aika is stuck in bed after catching a cold. She wonders about Akari and Alice... Are they slacking off without her? Surely they're lost without her guidance! So she sneaks out of bed one day to go take a peek... Later, Aika has a cute new set of hairpins, and she'd like to show them to Al. But she can't find the chance to visit him, and it's bothering her more than it should. Why does her heart ache when she thinks about it?

In the still of the night, Akari is woken up by the distant sound of a train. But Neo-Venezia's trains don't run at that hour, so what was it she heard? And to make matters even more mysterious, the next day, President Aria gifts her with a train ticket. It would seem Akari is about to have another brush with the secretive spirit, Cait Sith...