Parasite Eve

Parasite Eve is a 1997 Japanese science fiction film that was directed by Masayuki Ochiai and is based on the 1995 novel Parasite Eve by Hideaki Sena. Kiyomi, the wife of Toshiaki Nagashima, is left brain dead after a traffic accident on the day of their first wedding anniversary. Nagashima attempts to make Kiyomi live again by making a deal with a doctor who wants to harvest Kiyomi's kidneys for transplanting into a young girl in the same hospital. Nagashima agrees on the condition that he can have his wife's liver. While Nagashima experiments with the organ, the doctor finds one night the samples have emerged as a gelatinous form in the form of Toshiaki's dead wife and reveal themselves as an organization of sentient mitochondria that are bent on making a new species that will wipe out humanity.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.

Poster © the film's rights holders.