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?

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!

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.