ARIA The ORIGINATION: Sono Choppiri Himitsu no Basho ni...

Special episode based on chapter 39 (or Navigation 39) entitled "The Secret Place". Its action takes place between episodes 5 and 6 of Aria the Origination.
Akari and President Aria take a walk in the eastern part of Neo-Venezia. They are spotted by Akatsuki, who follows them to try to greet Akari. They eventually end up at St Mark's Basilica, where Akari has a secret place, which is discovered by Akatsuki, Aika, and Alice.
(Source: Wikipedia)