In a country where ghosts are traditionally believed to hide in the loo, a Japanese company is advertising a new literary experience, a horror story printed on toilet paper. Each roll carries several copies of a new nine-chapter novella written by Koji Suzuki, the Japanese author of the horror story “Ring,” which has been made into movies in both Japan and Hollywood. “Drop,” set in a public restroom, takes up about three feet (90 centimeters) of a roll and can be read in just a few minutes, according to the manufacturer, Hayashi Paper.