When a rare species of butterfly is found in a mysterious valley in Japan, a pair of entomologists go to investigate and find more. They discover Varan, a giant monster, who decides to leave the valley and head straight for Tokyo.

Kōzō Nomuraas Kenji Uozaki
Ayumi Sonodaas Yuriko Shinjô
Koreya Sendaas Dr. Sugimoto
Akihiko Hirataas Dr. Fujimora
Fuyuki Murakamias Dr. Majima
Yoshio Tsuchiyaas Military Officer Katsumoto
Minosuke Yamadaas Secretary of Defense
Hisaya Itoas Ichiro
Yoshibumi Tajimaas Captain of Uranami
Nadao Kirinoas Yutaka Wada
Hajime Koizumi