Kairo, known more commonly as Pulse, is a 2001 horror film by Kiyoshi Kurosawa. Kairo did well upon its release, received positive critical reviews, and has since gained cult status. There was even an American remake of the film in 2006 which spawned several sequels in the franchise. You'll never look at the internet the same again.

In Kairo, two storylines follow a central theme about malevolent spirits that are able to invade the world of the living through the Internet. Kudo (Kumiko Aso) is a plant shop assistant who notices her coworker has been missing for several days. When she checks up on him, she realizes that he is acting unnaturally. After he commits suicide in front of her, Kudo and her friends become convinced that a computer disk he left behind is what caused his mysterious and sudden death. In the parallel story, Ryosuke (Haruhiko Kato) becomes haunted by a strange website that he can't escape after signing up for a new service provider. When his friend begins to act strangely, similar to Kudo's coworker, he discovers the truth behind what's been coming through the computer screen.