Ultraman: S1 E5 - The Secret Of The Miroganda Ultraman
A strange incident occurred, that the members of Oilys Island Investigation Team suffocated to death. Professor Yamada, one of the victims of this incident, irradiated the plant "Miroganda" brought back from the island, and this action caused it to become Green Monse. And this Green Monse was attacking the people who drank the water of Oiris Island! The only surviving woman of the investigation team is in danger!