She is a subordinate of Class Zero that sells items. She tends to be quiet and obedient, but sometimes cracks. According to the Crimson Codex, Aria is 15 years old and 145cm tall.
Aria accompanies Class Zero to Byakko sometime in the storyline; she is encouraged by King and Deuce to be more friendly, which results in her unveiling her true personality, that of a loud and cheerful young girl.
When the rest of Class Zero encounters a Crystal Jammer inside a Byakko government hall, she is seen flinging open the doors to that room and delivering a warning from Kurasame. Immediately afterward, she is tragically shot by a Byakko sniper and was presumed dead by Class Zero. But in actuality, she was brought to the Militan capital where she is healed before being placed under the watch of Qator Bashtar.
However, following after Qator's demise to prevent the Ultima Bullet from destroying the capital, Aria is found wandering around by two Byakko Soldiers. Because Qator had died, the Crystal erased all memories of him; Aria and the Byakko soldiers are bewildered and cannot recall that she had been put under the watch of the Brigadier General. Aria, remembering only that she originally came to Milites with Class Zero and was shot, recalls that someone saved her. However, the Byakko soldiers shoot her before she could say anything, leaving her motionless on the ground.