Toshirô Mifune plays a cop in postwar Tokyo who has suffered the humiliation of having a criminal take his gun from him, in one of Akira Kurosawa’s excellent early films. Before Akira Kurosawa became a world-famous director, there was a period right after World War II when he made his reputation in Japan with a series of inventive, socially conscious films. Among them was a police drama shot in 1949 called Stray Dog. A young cop, played by Toshirô Mifune, has his gun stolen from him on a crowded bus. Humiliated, he vows to track down the thief himself, and…