Researcher Asou Masaru and a slightly unbalanced scientist, Dr. Mochizuki are experimenting on the creation of a mysterious and vaguely threatening organism. Along the way, he pauses to create a human/locust cyborg out of Asou. Alarmed at his new form, the now ZO retreats to a nearby forest and hides away. In the meantime, Dr. Mochizuki has finished his work and the organism is set loose on an unprepared world. ZO returns to defend the deranged scientist's young son and the world in a series of battles.