"The Earth is threatened with atomic destruction if the people of Mirapolia (sic) are not allowed to rule the planet. Observers from a distant planet, fat off in space, have been observing Earth and see the peril it's (sic) facing. Hoping to offer aid to the citizens of Earth, the benevolent aliens send their champion Starman to face off against the leaders of Mirapolia (it's correctly spelled Merapolia) and take care of their atomic weapons," according to the DVD sleeve's synopsis.
Ken Utsui (as Sûpâ Jaiantsu, or Super Giant) must save the Earth from nuclear peril. This is the American (English edited and dubbed) version of the Japanese super-hero's earliest movies, Sûpâ jaiantsu (1957) and Zoku sûpâ jaiantsu (1957). Herein, Mr. Utsui is Starman of "The Emerald Planet". Considering the material, this is a sometimes surprisingly well-directed, by Teruo Ishii, piece of super-nonsense; the location scenes are most enjoyable. Otherwise, it's, at best, unintentionally funny.
Watch for the scene where Utsui goes to a church with some children, and meets a nun. She gives him a smile that shows she's attracted to him; then, the young nun looks down at Utsui's groin area, where he has positioned his gun. Oh, sister!
*** Atomic Rulers (1964) Teruo Ishii ~ Ken Utsui, Utako Mitsuya, Junko Ikeuchi