In the West, the original 1995 novel's relatively obscure and didn't get an English translation for nearly a decade. In Japan, though, it was a smash hit and one of the catalysts of the J-horror phenomenon of the late 1990s and early 2000s, alongside Ringu and Ju-on.

This film was released in 1997, but what made the franchise famous internationally was the 1998 PlayStation computer game, a cult classic and an early landmark in the Survival Horror genre.

It's about sentient mitochondria. This is hilarious, but never mind. That's the premise. What can you do? In reality, mitochondria are organelles in eukaryotic cells that generate most of the cell's energy supply through aerobic respiration. They have a double membrane, contain their own DNA and are important in cellular function. In this film, though, mitochondria is a gestalt organism or has a group mind or something. It says it's been waiting for a billion years. "At last, mitochondria will be free! We have known you since you were microorganisms."

The downside of this happy family reunion is that the mitochondria thinks it can now reproduce directly, so it's planning to make us extinct.

The human characters include Toshiaki Nagashima (Hiroshi Mikami) and his wife Kiyomi (Riona Hazuki), who has a traffic accident on their first wedding anniversary. She's left brain dead. Fortunately, though... (a) her kidneys might help a young girl who needs a transplant, and (b) there might be revolutionary medical possibilities!

The special effects are dodgy. There's 1997 CGI fire, because Parasite Eve can burn people by looking at them. There's a hilariously bad shot when an eagle eats a snail (although it's true that eagles sometimes do that). Worst of all, though, is the nipple-less nudity of Riona Hazuki. The director had been worried about her fans just wanting to see her naked and so hoped this might look "sexual" and "bizarre and horrific without being exploitative". Actually, it just looks like a skin-coloured top or something. Boobs with no nipples are always rubbish in anime and they're a failure here too.

Frankly, I'd avoid getting your hopes up. Comparisons with Ju-on and Ringu are telling. 1998 was when those film series began (not counting a 1995 Ringu TV adaptation) and J-horror exploded. This film appeared the year before that and you'll be disappointed if you compare it with those horror landmarks. The film's lighter and less nightmarish than the original novel. Even the film's director was unhappy with how it turned out, complaining that the producers had pushed him to make it more of a love story. There were "so many compromises I had to make that it couldn't be a true horror movie".

This would have been a darker film two or three years later, once the Japanese film industry had identified its new bandwagon.

It's okay, though. I don't dislike it. It has its own kind of slow-building atmosphere and I'll always have a soft spot for deliberately paced horror-tinged SF that thinks it's cerebral but is in fact bonkers. The romantic angle is odd, but sincere and original. You've got to love a film where the hero offers to hug his wife and she emotionally accepts... despite having just set his arms on fire. I'd had this on my "to watch" list for years, actually, and I'm pleased I finally got around to seeing it.