Aoto is a steeplejack apprentice and the main protagonist of Ar tonelico Qoga: Knell of Ar Ciel. He was training to be a steeplejack under the guidance of Steeps, his foster father, when he meets Saki, a mysterious woman who has no idea who she is. Stuck in a struggle between Archia and Clustania, Aoto takes Saki to Hikari Gojō, a doctor specialized in Reyvateils.
Undaunted by seemingly absolute hopelessness and a strong sense of responsibility, he never surrenders to his will and he keeps trying. That is probably why he is loved and supported by so many people that he encounters.