In the two years following the release of Horse in 1941, Kurosawa searched for a story he could use to launch his directing career. Towards the end of 1942, about a year after the Japanese attack on Pearl Harbor, novelist Tsuneo Tomita published his Musashi Miyamoto-inspired judo novel, Sanshiro Sugata, the advertisements for which intrigued Kurosawa. He bought the book on its publication day, devoured it in one sitting, and immediately asked Toho to secure the film rights. Kurosawa's initial instinct proved correct as, within a few days, three other major Japanese studios also offered to buy the rights. Toho prevailed, and Kurosawa began pre-production on his debut work as director.
Shooting of Sanshiro Sugata began on location in Yokohama in December 1942. Production proceeded smoothly, but getting the completed film past the censors was an entirely different matter. The censorship office considered the work to be objectionably "British-American" by the standards of wartime Japan, and it was only through the intervention of director Yasujir Ozu, who championed the film, that Sanshiro Sugata was finally accepted for release on March 25, 1943. (Kurosawa had just turned 33.) The movie became both a critical and commercial success. Nevertheless, the censorship office would later decide to cut out some 18 minutes of footage, much of which is now considered lost.
He next turned to the subject of wartime female factory workers in The Most Beautiful, a propaganda film which he shot in a semi-documentary style in early 1944. In order to coax realistic performances from his actresses, the director had them live in a real factory during the shoot, eat the factory food and call each other by their character names. He would use similar methods with his performers throughout his career.
During production, the actress playing the leader of the factory workers, Yko Yaguchi, was chosen by her colleagues to present their demands to the director. She and Kurosawa were constantly at loggerheads, and it was through these arguments that the two, paradoxically, became close. They married on May 21, 1945, with Yaguchi two months pregnant (she never resumed her acting career), and the couple would remain together until her death in 1985. They would have two children: a son, Hisao, born December 20, 1945, who would serve as producer on some of his father's last projects, and Kazuko, a daughter, born April 29, 1954, who would become a costume designer.
Shortly before his marriage, Kurosawa was pressured by the studio against his will to direct a sequel to his debut film. The often blatantly propagandistic Sanshiro Sugata Part II, which premiered in May 1945, is generally considered one of his weakest pictures.
Kurosawa decided to write the script for a film that would be both censor-friendly and less expensive to produce. The Men Who Tread on the Tiger's Tail, based on the Kabuki play Kanjinch and starring the comedian Enoken, with whom Kurosawa had often worked during his assistant director days, was completed in September 1945. By this time, Japan had surrendered and the occupation of Japan had begun. The new American censors interpreted the values allegedly promoted in the picture as overly "feudal" and banned the work. (It would not be released until 1952, the year another Kurosawa film, Ikiru, was also released.) Ironically, while in production, the film had already been savaged by Japanese wartime censors as too Western and "democratic" (they particularly disliked the comic porter played by Enoken), so the movie most probably would not have seen the light of day even if the war had continued beyond its completion.