''Kairo'', also known as ''Pulse'' (or sometimes ''Circuit'') in English, is a 2001 horror film by Creator/KiyoshiKurosawa.

During the computer boom of the early 2000's, people around the world are more connected than ever... but they might also be more isolated than they realize. Michi Kudo, a young worker who just moved to Tokyo, finds herself plagued by strange and frightening events that seem somehow connected to computers and the internet after one of her coworkers kills himself. Meanwhile, a college student named Ryosuke Kawashima has noticed his own computer exhibiting strange behavior and showing him video of people alone in dark rooms, acting bizarrely. As disappearances, suicides, disasters, and ghost sightings begin to pile up around them, Michi and Ryosuke struggle to find an explanation for what is happening and if it's even possible to stop it.

An American remake titled ''Pulse'' (no relation to [[Film/{{Pulse}} the 1988 horror film of the same name]]) was released in 2006, starring Creator/KristenBell, Creator/IanSomerhalder, and Christina Milian, and was followed by two sequels, both released in 2008. Kurosawa himself later adapted the script into a novel.

Not to be confused with the video game ''VideoGame/{{Kairo}}''.

!!Contains examples of:
* AdultFear: The fear of isolation and dying alone, and the fear of technology ruining or irrevocably altering life as we know it in ways that can't be controlled.
* ApocalypseHow: By the end of the film, we learn that [[spoiler:events similar to those in Tokyo are taking place all over the world, implying at least a Class 2 disaster.]]
* DownerEnding: When all is said and done, [[spoiler:Tokyo and likely most or all of Japan are in ruins, we've learned that similar things are happening all over the world, Ryosuke is dead or [[FateWorseThanDeath worse]], and Michi is the only named character who is for sure still alive, and her eventual fate is uncertain.]]
* DrivenToSuicide: Michi's coworker Taguchi, followed by others throughout the film.
* DwindlingParty: One by one, the characters that we meet begin to die or disappear until only Ryosuke and Michi are left.
* HauntedTechnology: Pretty much every computer, disk, or any other technology is most likely infested with ghosts.
* MindScrew: Even if you understand the basic premise of what is happening, the movie is confusing and keeps the viewer off-balance.
* NewMediaAreEvil / NewTechnologyIsEvil: Though it's not the computers or internet themselves that are evil, it's that [[ItMakesSenseInContext they're allowing ghosts to invade the living.]]
* NothingIsScarier: Long stretches of the film are quiet, slow, and serve only to ramp up the tension. Even when things ''do'' start to pick up, the viewer isn't left with many answers.
* PsychologicalHorror
* SealedEvilInACan: Sealing up doors with red tape when someone within has killed themselves or vanished seems to keep the ghosts contained. The problem is that [[IdiotBall other people keep opening the doors anyway.]]