Mayonaka no Occult Koumuin Miyako Arata is newly assigned to the Shinjuku Ward Office's Nighttime Regional Relations Department. Each of Tokyo's 23 wards has one such department, established to mitigate paranormal and occult-related events. Arata's special skill is the understanding of non-human speech, and the story begins with him encountering a youkai at Shinjuku Gyoen park who refers to him as the legendary Heian-era exorcist, Abe no Seimei.