Akuma wa Yurikago wo Utau

Chicchi brothers who are exorcists who save people who are possessed by an unknown virus known as "Devil". Contagious through fear, this "devil" continues to move from person to person and cannot be eradicated by ordinary exorcists. However, except for this brother, a rogue exorcist who is out of the Vatican's jurisdiction. (Source: Kadokawa, translated)