Demon Beast Invasion (Revenge of the Demon Beast) (1990)

100 million years ago, an ecological disaster drove the Demon Beasts from our world. Now they must breed with human females to create a new, hybrid creature who will clear the way for an invading horde. When 19-year-old Kayo is raped by a possessed lover, it's up to 19-year-old Interplanetary Mutual Observation Agent Muneto to save her from the terrifying creature to which she gives birth: A mutant, lust-driven Demon Beast!