Skull Man

Set in an alternate history of Japan, freelance photographer Minagami Hayato returns to his hometown of Ootomo to investigate rumors of a man wearing a skull mask committing murders there. Once in the city, he discovers connections between the victims and a local pharmaceutical company, a new religious sect, and strange half human, half animal creatures. Along with a young photographer, he decides to find out who the Skull Man really is.

(Source: Baka-Updates Manga)