Black River (1957)

Perhaps Kobayashi's most sordid film, Black River is an exposé of the rampant corruption on and around U.S. military bases following World War II. Kobayashi spirals out from the story of a love triangle that develops between a good-natured student, his innocent girlfriend, and a coldhearted petty criminal (Tatsuya Nakadai, in his first major role) to diagnose a social disease that had Japan slowly succumbing to lawlessness, devolving into gangsterism, violence, and prostitution.