Iona Musashi is the mental model (humanoid avatar) of the Japanese submarine I-401 from the anime series Aoki Hagane no Arpeggio: Ars Nova. Iona serves as the main female protagonist and the loyal companion to Gunzō Chihaya, the captain of the Blue Steel fleet. She is characterized by her calm demeanor, logical thinking, and deepening sense of individuality as the story progresses. Iona’s evolving relationship with her crew and her quest for understanding humanity are central to the plot.