Akatsuki Izumo is an apprentice Salamander responsible for maintaining the climate within the floating structures above Aqua. His visits to the surface of Neo-Venezia are rare, making each descent a notable event. He possesses a tall stature and a typically impatient demeanor.

He frequently teases Akari Mizunashi, mocking her by using the nicknames "Pigtails" or "Sideburns," much to her displeasure. Despite this habit, he spends a considerable amount of his time in Neo-Venezia in her company, irrespective of his official reasons for being there.

Akatsuki professes strong feelings for Alicia Florence, often calling Aria Company solely to hear her answering machine message. However, both Alicia and his older brother imply his true attraction may lie with Akari. During his interactions with Alicia, he displays uncharacteristically polite and well-mannered behavior.

In appearance, he has black hair and eyes, with his hair often worn in a ponytail or loose to his shoulders. He typically dresses in a loose-fitting robe or a jacket with a turtleneck, garments that often conceal his features. A constant scowl further masks his appearance, though he is drawn with bishōnen qualities.

He has an older brother who regularly teases him, frequently provoking a strong reaction. His social circle includes Woody, a childhood friend, and Al, a gnome. His association with Al sometimes causes consternation for Aika, who does not regard him highly.

His duties as a Salamander apprentice involve critical climate control work above Aqua, which restricts his time on the ground. On one visit, Akari persuaded him to walk barefoot through the waterlogged streets during Aqua Alta, an experience he found unexpectedly enjoyable.