Ichi the Killer (2001)

When a yakuza boss goes missing one of his underlings, Kakihara (Tadanobu Asano) makes it his mission to find out who’s responsible. A masochist at heart, Kakihara is intrigued by the trail of blood and guts which eventually leads him to Ichi (Nao Omori) - a brain-washed killer with an immeasurable potential for destruction and a highly unstable personality to go along with it.