Parasite Eve is a Japanese novel by Hideaki Sena, first published in Kadokawa Horror Bunko.
It was later adapted into a film in 1997, with a heavier focus on romance than horror.
In 1998, the video game was released for the Sony PlayStation by Squaresoft, now known as Square Enix, as the sequel to the novel. A sequel to the game was released in 1999, also for the PlayStation.
To continue with the idea of the manga for the video game, a manga was produced of the novel to tell the events for those gamers who had not read the novel.
Mitochondria are the "energy factories" of biological cells. It is thought that they were originally separate organisms, and a symbiotic relationship between them and early cellular life has evolved into their present position as cell organelles with no independent existence through the female line of descent, form the dispersed body of an intelligent conscious lifeform, dubbed Eve (more accurately Eve 1), which has been waiting throughout history and evolution for the right conditions when mitochondrial life can achieve its true potential and take over from eukaryotic lifeforms (i.e. humans and similar life) by causing a child to be born that can control its own genetic code.
Eve is able to control people's minds and bodies by signaling to the mitochondria in their bodies. She can cause certain thoughts to occur to them and also make them undergo spontaneous combustion.
The conditions Eve has waited for have arrived; she has found the perfect host in the body of Kiyomi Nagashima. At the start of the book, Eve is the mitochondria in Kiyomi's body. She causes Kiyomi to crash her car; Kiyomi survives but is brain dead. Kiyomi's husband is Toshiaki Nagashima, a research assistant teaching and researching biological science. Eve influences Toshiaki and a doctor to ensure that one of Kiyomi's kidneys is transplanted into the teenage girl Mariko Anzai as an organ donation. As part of Kiyomi's body the kidney is part of Eve. It prepares Mariko to be a suitable host for giving birth to mitochondrial life (her immune system would otherwise rebel against this).
Eve influences Toshiaki to grow some of Kiyomi's liver cells in his lab in sufficient quantities to provide Eve with an independent body, he thinks that he is doing this as an experiment using different cultures of the liver cells. Forming some of the cells into a body, Eve possesses Toshiaki's assistant Sachiko Asakura and intermittently takes control of Asakura to work upon the cultures. Eventually, she takes control of Asakura during a conference presentation speech and announces her presence. Leaving Asakura's body, she returns to the lab. Toshiaki pursues her, and she attacks him in the form of Kiyomi to capture some of his sperm, which she uses to fertilise an egg of her own production. Moving to the hospital, she implants this zygote in Mariko's womb. The embryo develops into an offspring that is born almost immediately.
Eve anticipates that her child will be able to consciously change its genetic code, thus being an infinitely adaptable "perfect lifeform" capable of replacing humanity and similar eukaryotes. Mariko's body will be host to a new race of these lifeforms. The experiment fails, since Toshiaki's sperm carry a separate line of "male" mitochondria (inherited through sperm) that will be wiped out in the new order; these resist the change by fighting for control of the child's body, causing it to switch between male and female forms. The child dies; Toshiaki also dies, merging his body with the child's to control the bursts of psychokinetic-like power it gives out in its death throes that threaten to kill many people.
In the novel's epilogue, it is revealed that some samples of the Eve cells in Toshiaki's lab survived. Fortunately, they are destroyed shortly after being found.
In reality, most of the original mitochondrial genome has been lost or transferred to the host cell nucleus. Only 36 confirmed genome remain. As a result, the evolutionary potential of mitochondria is actually very limited, which is how it was possible to develop the molecular clock required to approximate when the “mitochondrial Eve” would have lived. The concept of a “mitochondrial Eve” is in itself misleading since it does not actually refer to a single woman. Instead, the “mitochondrial Eve” is the most-recent common ancestor of all humans alive on Earth today with respect to matrilineal descent.
The genesis of the mitochondrion was not in humans but in a species thought to be similar to bacteria. Regardless, mitochondria cannot survive without the constant supply of biomolecules and environment provided by the host cell. While mitochondria are linked to certain diseases and cell death, they cannot “rebel”. Also, the concept of rebellion implies conscious action, and even under the most generous terms mitochondria would not be attributed with the level of intelligence required for rebellion, much less the fantastic powers they have in Parasite Eve.