Demonic Possession? It's Just a Parasite

Whether it is UMA or urban legends, they are not unusual existences under the shadow of this bustling steel jungle. However, since a group of religious fanatics who once shocked the world held bizarre rituals, there have been more and more sighting records of creatures recorded in occult science, evil objects recorded in ancient mythology books, and even monsters created in modern books. Humans are unprepared...? As early as hundreds of years ago, the "Exorcists" who gained titles such as "The Line of Defense between Reality and Mystery" and "The Night Army" have been maintaining the balance of the world. ... The young man thought that these would have nothing to do with him in his life. However, after being possessed by the demon Abaddon, in order to protect his sister, he pierced his heart with a holy nail made by his knowledge of potions and mythology. He had to accept the fact that he gave up his original life and became an exorcist in order to expel the "parasites" from his body. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.