Distortion: Shikabano Oni no Joou (Volume)

is the first volume of the Distortion: Shikabano Oni no Joou light novel series, written by Keisuke Okada and Illustrated by Haruyuki Morisawa. It was released under the Dengeki Bunko Imprint in April 2007.

Synopsis
Kazuma, a high school student, goes back to a horror movie with Rimi, the eldest daughter of three sisters next door, and is attacked by a monster that looks a lot like the "Shiki" that appeared in the movie. Kazuma was seriously injured and Rimi was taken away by a monster ... Six months later, Rimi's younger sister, Masaki, goes missing, and a boy, Yoshito, with a guitar appears in front of Kazuma, who desperately searches for his whereabouts. He summoned a terrifying purgatory angel and told Kazuma to burn a flock of corpses. "Reality is easily distorted and broken. Anything is allowed to exist in a broken reality. Shiki or whatever." It is a parasite "exciter" that distorts reality and embodies nightmares. It was the beginning of the battle ...

(source: Amazon JP - Translated)