Iona Takao, known as イオナ 高雄 in Japanese, is a central character in the anime series Aoki Hagane no Arpeggio: Ars Nova. She is the Mental Model of the submarine I-401, exhibiting human-like characteristics and emotions. Iona is known for her calm demeanor and unwavering loyalty to her captain, Gunzo Chihaya. Throughout the series, she plays a crucial role in battles against the Fleet of Fog and aids in strategizing against formidable opponents. Her character explores themes of identity and autonomy as she develops her own sense of self.