It was when Hisao Mesaki, now 85, returned to Japan from Saipan in early 1941 with his parents and siblings that an offhand remark to his new classmates aroused suspicion he was from a family of spies.

They had been living in Saipan since the spring of 1940, with Mesaki's father working in the shipping industry. But they were told by the Japanese government to return, as Tokyo was preparing for war with the United States and Britain in addition to the ongoing conflict with China. Pacific islands including Saipan were likely to become battlefields.

When he entered a Tokyo elementary school as a second-grader, Mesaki was asked by his classmates why he returned to Japan. Without thinking too much about it, he repeated what he had heard from his parents: "We left because Japan is soon going to war with the United States and Britain."