An eminent biologist, Dr. Murayama, discovers a new clean energy source, and Destron's Machinegun-Snake is sent to seize the data. Failing to grab the doctor, he kidnaps assistant Nishizaki Michiko. When she refuses to talk, Machinegun-Snake targets Tsutomu, her son. Kazami Shiro is injured by the mutant! Can V3 protect Tsutomu, his friend Mamoru, and rescue his mother?