Nanami Miura, a 26-year-old woman residing near the Mutoh family, works as both a personal trainer and at an osteopathic clinic, with martial arts among her hobbies. She evacuates Tokyo alongside the Mutoh family following catastrophic earthquakes. During the journey, she demonstrates practical conflict resolution. When a confrontational truck driver attempts to assault her, Nanami utilizes her martial arts training to defend herself. Mari Mutoh intervenes, aiding Nanami in incapacitating the driver and commandeering his vehicle. Nanami later gives the driver’s glasses to Haruo Koga to replace his damaged pair.

Her death occurs in a mountainous region when the group encounters poisonous gas released by geological instability. While accompanying Ayumu Mutoh during a break, Nanami collapses after exposure. A paramotor operator named Kite arrives, warns Ayumu to stay back, and confirms Nanami's rapid death due to the toxic fumes. Ayumu subsequently experiences guilt over the incident. Unaffected by the gas, the rest of the group continues their journey.