18+ Niku: Danzai

One year after a group of three university students vanished in a certain region of Tohoku, Katsumi, a private detective, receives a request to find someone's missing son. Blinded by the exorbitant compensation, Katsumi heads to a certain town in Tohoku, only to find a hellish world of blood and carnal desire, where common sense does not prevail.

(Source: Shogakukan, translated)