The Night Beyond the Tricornered Window(さんかく窓の外側は夜)

Kosuke Mikado, who works at a bookstore, has been suffering from a peculiar constitution that ghosts can see from an early age. One day, Kosuke was invited by a exorcist, Rihito Hiyakawa, who came to the bookstore and decided to work with him. The two men, who were requested by the detective Hanzawa to investigate the serial murder case that occurred a year ago, eventually found a body, but the body was cursed. While searching for the truth, they often hear the voice of the murderer who committed suicide...