The genre has largely become the stuff of parody now, but back in the late-90s/early-00s, Ringu (The Ring) and Ju-On (The Grudge) kicked off a brand new epoch in the Japanese horror-film genre. Blending ancient folklore and ghost-stories unique to Japanese culture with present-day urban legends and classical haunted-house trappings, the startling results terrified audiences, gave horror fans a new set of iconic ghosts to fear and spawned numerous sequels, similar features like Dark Water and a pair of successful American remakes. However, both series have been dormant for several years... until now.
Believe it or not, Kadokawa Productions and NBC/Universal are reviving the respective evil spirits of both films, Sadako (Ring) and Kayako (Grudge) for a crossover battle: Sadako vs. Kayako, aka. The Ring vs. The Grudge.
Amusingly, the producers were inspired to create the film after a fan-made teaser for an imaginary "Ring vs Grudge" movie was posted online as a joke but became a viral sensation in Japan. While the so-called "J-Horror" genre ultimately went out of fashion in the West, in its native Japan both films are still regarded as modern horror classics - their signature minimalist visual cues and sound-effects guaranteed to give fans the willies even today. It's entirely plausible (and, indeed, Kadokawa is banking on it) that the prospect of seeing these two iconic "hair-scare" horror figures (three, if you count Kayako's mischievous child/cat helper, seen lurking on the film's official poster) meet and match wits is as big a deal to a generation of Japanese horror fans as Freddy Vs Jason was to Western slasher devotees.
Left unsaid is exactly what the plot of the film will be, beyond that a human girl named Yuri will be caught up in the battle between the two ghouls. It should be interesting, at least, to find out exactly why Sadako and Kayako would be fighting and (for that matter) exactly how their respective abilities line up - especially considering that both are closer in nature to "manifestations" than singular entities unto themselves.
In case your memory needs a refresher: Sadako is the vengeful ghost of a young girl with malevolent psychic abilities who was buried in a well decades ago and now menaces the world via haunted VHS tapes that display cryptic surreal images and mark the watcher for death at her hands a week later unless they pass the video "virus" to someone else. Kayako, on the other hand, is one of multiple manifestations haunting a suburban Japanese house where a violent murder-suicide claimed the lives of an entire family; leaving behind a trio of violent specters born of the extreme rage and pain unleashed during their respective deaths. While Sadako has been known to manipulate objects and "travel" via electronic signals to stalk her prey, Kayako typically takes on the physical form of a crawling, waterlogged corpse who "speaks" only in a gutterall rattle and is capable of chasing down and slaughtering anyone who enters "her" house - even if they initially escape.
The actual "rules" of both ghost's powers are somewhat fluid from installment to installment, and the crossover appears to be playing things more for iconography and fun than any kind of serious examination of either series supernatural themes - with the trailer even including a shot of Kayako's hand crushing one of Sadako's tapes.
Sadako vs. Kayako (aka The Ring vs. The Grudge) is due out in Japan in June. No indication of a U.S. release is available at this time.