Rear male nudity in some scenes. We see buttocks.

We see bare breasts on a corpse in a mortuary.

A man masturbates during shower.

A few bloody stabbings with blood shown on clothes.

Some martial arts style fights sequences, these are quite long and intense, but what you would expect in an action film.

During a mortuary scene we see bodies with multiple stab wounds.

Fairly frequent use of fuck and mother fucker.

Frequent cigarette smoking, some alcohol drinking, verbal references to drug dealing, but nothing is shown.

Kyu-hwan kills his parents this scene can be scared for some viewers