In 'Ura Jutaijima', the seemingly idyllic vacation of a group of friends on a remote island descends into a horrifying spiral of sexual debauchery and monstrous breeding. The island is inhabited by grotesque, tentacled creatures driven by an insatiable lust to impregnate human females. One by one, the women are captured and subjected to relentless, non-consensual impregnation rituals. The series graphically details their physical and psychological violation as they are forcibly inseminated, their bodies used as breeding vessels for the island's monstrous inhabitants. The men watch helplessly, or are themselves brutalized, as their friends and lovers are turned into broodmothers, their wombs swelling with alien seed in a nightmarish spectacle of forced impregnation and creature-based orgies.