Mofu Usaki is a world-renowned neurosurgeon who operates on a microscopic scale and performs at least eight hundred surgeries each year. She also hosts a live show called Lie or Truth? ESP!! Within the story, she serves as the personal physician of Ron Kamonohashi, compounding the medication that suppresses his dangerous compulsion to drive criminals toward self-destruction. Despite her extraordinary medical expertise, Mofu is notably lacking in basic life skills and is often seen covered in bandages from her own frequent small accidents. She maintains a cheerful and determined demeanor even in the face of these mishaps. Her motivations are rooted in genuine care for her patient and a supportive nature; after learning about Ron and Totomaru Isshiki’s partnership, she chooses to aid them and becomes one of Ron’s few trusted allies. She visits Ron on the day of his discharge from the hospital and continues to support him through his troubles. In her interactions, she refers to Ron simply by his family name. Her key relationships include Ron, for whom she acts as doctor and confidante, and Totomaru, whom she assists alongside Ron. Her development remains steady rather than transformative, as she consistently provides medical and emotional backing without major personal arcs. Her notable abilities include her unmatched skill in microsurgery and her capacity to formulate the specialized medication necessary to keep Ron’s condition under control.