Tatsuo Osako worked as a clerk for the Japan Tourist Bureau in the foreign tourist department. In 1940 he served as assistant purser of the old 2000 tonnage ship called Amakusa Maru that went from Tsuruga to Vladivostok bringing Jewish refugees to Japan. Following the German invasion of Poland, thousands of Jewish refugees crossed the border into the Soviet Union. With the help of Japanese counsel Chiune Sugihara, many then obtained Japanese transit visas. They crossed through the Soviet Union on the Transiberian Railroad en route to Japan. Prior to the American entry into World War II, American Jewish organizations asked the Japan Tourist Bureau to serve on their behalf to channel aid to the refugees. The American Jewish organizations sent money and papers via the Walter Brown Company (later Thomas Cook) to distribute to the refugees to pay for their transit and expenses. The Japanese Tourist Bureau also arranged to transport the refugees by ship from the Soviet Union to Japan. From September 10, 1940 to June 1941, Osako sailed every two weeks across the wintry Japan Sea helping to escort over 2,000 Jewish people to safety. Once on board Osako had to check to make sure passengers had proper immigration papers and visas and whether Thomas Cook Co. had paid for the remittance. If the remittance did not come, then the American Jewish Society in Kobe came and guaranteed their expenses. Many of the refugees whom Osako helped gave him their photographs (later collected in an album) with inscriptions of gratitude.