Shooting began in early December, but Kurosawa would last only a little over three weeks as director. He struggled to work with an unfamiliar crew and the requirements of a Hollywood production, while his working methods puzzled his American producers, who ultimately concluded that the director must be mentally ill. Kurosawa was examined at Kyoto University Hospital by a neuropsychologist, Dr. Murakami, whose diagnosis was forwarded to Darryl Zanuck and Richard Zanuck at Fox studios indicating a diagnosis of neurasthenia stating that, "He is suffering from disturbance of sleep, agitated with feelings of anxiety and in manic excitement caused by the above mentioned illness. It is necessary for him to have rest and medical treatment for more than two months." On Christmas Eve 1968, the Americans announced that Kurosawa had left the production due to "fatigue", effectively firing him. He was ultimately replaced, for the film's Japanese sequences, with two directors, Kinji Fukasaku and Toshio Masuda.