Lisa Mishima is a high school student who becomes entangled in the terrorist activities of Nine and Twelve, the duo known as Sphinx. She is a quiet, shy, and clumsy girl whose introverted nature makes her an easy target for bullying at school. Her home life is equally troubled: she lives with her emotionally unstable and overprotective mother, who fears abandonment after Lisa’s father left the family. This environment leaves Lisa deeply isolated, anxious, and lacking self-worth, to the point where she contemplates disappearing entirely.

Her motivations are rooted in a desperate need for belonging and acceptance. When Twelve rescues her from bullying and later offers her a choice to join them, she feels an immediate connection, sensing that they share a common alienation. Her primary drive becomes the desire to escape her oppressive home and school life, and to find a place where she matters. This need for connection is also intertwined with a deep fear of abandonment, which makes her cling to the kindness shown by Twelve.

In the story, Lisa serves as the emotional core and the humanizing element for Nine and Twelve. While they are genius-level strategists driven by their past trauma and a mission to expose the truth, Lisa represents ordinary suffering and the civilian perspective. Her presence introduces unpredictability and emotional warmth into their cold, logical world. She is initially a passive figure, but over the course of the series she develops a quiet resilience. She begins to stand up for herself, confront her mother, and take active steps to survive. Her most significant role is that of a witness: by the end, she is the only one left to remember Nine and Twelve and to carry the truth of their existence.

Key relationships define her character arc. Her bond with Twelve is the most affectionate and transformative. Twelve shows her consistent kindness, saves her from drowning, teaches her to ride a motorcycle, and reassures her when she feels useless. This relationship gives her a sense of worth and stability. In contrast, Nine initially sees her as a liability and a burden, often treating her with cold indifference. Over time, however, she earns his reluctant respect by proving she can be useful, such as when she carries out a mission task despite being captured later. Her relationship with her mother is fraught with tension and emotional abuse, but a confrontation in episode 5 marks a turning point where Lisa begins to assert her own will. She is also targeted by the antagonist Five, who uses her as a hostage to get to the boys, further testing her resolve.

Lisa’s development is subtle but clear: she evolves from a helpless, bullied outcast who cannot swim and feels invisible into someone who chooses to keep living despite immense loss. She gains no combat skills or supernatural abilities; her strengths lie in her emotional intelligence, empathy, and growing courage to face danger. She learns to ride a motorcycle, to follow orders in a crisis, and ultimately to survive on her own. By the series finale, after witnessing Twelve’s execution and Nine’s sacrifice, she is left alone but no longer broken—she has found the will to live and carries the memory of the two boys as a promise.

Notable abilities are limited to her emotional resilience and her capacity for connection. She does not possess technical hacking skills, combat prowess, or any extraordinary talents. Her clumsiness and lack of physical coordination are highlighted early on, but she compensates through perseverance and a deep-seated need to be useful. Her most important contribution is her existence as a resonating human element that allows Nine and Twelve to feel something beyond their mission, and she fulfills the role of the ordinary person who bears witness to extraordinary events.