Nagisa Sagan  

, 目渚

Nagisa is an emotionally unstable woman who conducts experiments and creates humans without the ability to feel physical pain. Despite her youthful appearance, she is over 30 years old with an unknown background and affiliation. She had a sister, but her whereabouts are still uncertain. Nagisa created Youji in the likeness of her younger sister as a form of remembrance or to alleviate her emotional pain. Her eccentric behavior and lifestyle have made her isolated from others. She confides in Nana, revealing that she has no other friends. Her relationship with Ritsu is complex; while she appears to hate him deeply and wish for his failure, there are moments where her feelings towards him seem more intimate, as she blushes whenever he's near or touches her, despite denying any romantic interest. In volumes 3-4, Nagisa challenges Ritsu to a bet involving her older Zero pair, Yamato and Koya, against his Soubi. Despite their defeat, Nagisa continues to harbor a sibling rivalry-like attitude towards Ritsu.