Fifteen years after the battle with Puppetmaster, Nanaako, once a celebrated heroine, now lives a quiet life caring for the elderly Dr. Morisaki. However, her former comrade, Investigator Fubuki, suddenly appears and warns her that Puppetmaster has begun moving again. Though 35-year-old milf Nanaako feels the urge to fight, she suppresses it and decides to stay out of the conflict. But when Puppetmaster's conspiracy targets Dr. Morisaki's newly developed Beta System, Nanaako transforms into Cosplayer and returns to the battlefield. During the mission, Dr. Morisaki is taken hostage and Nanaako herself falls into enemy hands!