Ritsu is the heir of a famous novelist. His grandfather used to write supernatural stories and it was said he secretly worked with witchraft. More importantly, Ritsu's father who once ressuscitated from death is not really his father. His body is possessed by a spirit who sworn to his late grandfather to protect his grandson. Hyakkiyakou Shou follows the daily life and mysteries that Ritsu will encounter since he has the ability to see spirit. His first investigation involves his cousin Tsukasa.
