Iona is a central character in Aoki Hagane no Arpeggio: Ars Nova, serving as the mental model and avatar of the Fleet of Fog submarine I-401. Calm, enigmatic, and highly intelligent, she becomes the ally of Gunzou Chihaya and plays a key role in the series’ naval battles and strategic conflicts. Iona’s development centers on her growing individuality, emotional awareness, and loyalty, making her one of the most important figures in the story’s exploration of identity, humanity, and cooperation.