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!

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.

The mailman's gondola is being repaired, so just for today, Akari is making the rounds with him to get the job done. As she learns the ins and outs of what it means to be a mail carrier, she meets a boy who needs his letter delivered at any cost. Whatever the envelope he's holding contains, it's very close to his heart.

Akari, Aika and Alice have been given their latest assignment: they must host a party on the Festa del Redentore! It's a festival that marks the start of autumn, and it's celebrated with feasts and fireworks. They rent a large boat, and start brushing up on their hostess skills, but Akari can't help but be a little distracted. She hasn't heard from Ai in a while, and all her emails have gone unanswered...

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?