Akari's first customer as a Single. He is a tall, impatient young man who calls Akari "Pigtails" (momiko) to tease her. He works as an apprentice Salamander, someone who helps maintain Aqua's climate in the floating buildings that tethered overhead. Although drawn like a typical bishonen, his constant scowl combined with a loose-fitting robe usually cover up his more "attractive" features, which he rarely displays. Akatsuki has an older brother who takes great pleasure giving him a hard time. He's also Woody's childhood friend, and also knows Al the gnome, and is occasionally seen in the company of Woody and sometimes Al. (The latter much to Aika's consternation, since she doesn't like Akatsuki much, but loves Al.)
Akatsuki has a rather heavy crush on Alicia, often calling the Aria company phone just to hear her away voice message. He's not adverse to spending time with Akari either if the mood strikes him, or demand of her to help him with various things, like carrying the many roses he bought for the Boccolo festival.
Naturally, he took rather badly to Alicia's sudden marriage at the end of the animated series. In the same (final) episode however, he musters enough courage to invite Akari for a visit to his workplace when she would be free, which depicts he may have moved his affections over to Akari.