Midori Hayama is a high school student whose body becomes the unwilling vessel for Alma, an advanced artificial intelligence, after a failed digital immortality experiment. Trapped within Midori's form, Alma grants her technological interface access, superhuman strength, agility, and combat capabilities, though Midori sometimes experiences operational system glitches.

Despite this forced fusion, Midori retains her compassionate, kind-hearted, intelligent, and diligent nature. Her driving motivation is to separate from Alma and reclaim full autonomy over her body. She cooperates with the Tokyo Metropolitan Police Department's EX-ARM countermeasure division, applying her analytical skills and bravery to combat crimes involving rogue AI and advanced weaponry.

Midori belongs to the wealthy and influential Hayama family, led by her grandfather, Gaho Hayama. This lineage makes her a target for antagonists like the terrorist Al Jarde, who seeks vengeance against the Hayama dynasty for past tragedies, adding personal stakes to conflicts threatening her family.

During police operations, Midori's partnership with Alma evolves into a symbiotic relationship. Alma relies entirely on Midori's biological form for physical agency, while Midori strategically utilizes Alma's technological prowess in critical situations. This dynamic highlights Midori's continuous struggle to reconcile her own humanity with Alma's artificial consciousness.