That Undeliverable Letter... - S1.E4

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!