Prior to the Japanese attack on Pearl Harbor, and the United States' subsequent entry into World War II, Jeanne's family were fully committed to pursuing the American Dream. Despite living in a predominantly white neighborhood they don't feel in any way out of place. Jeanne's family are hard-working, law-abiding people who regard themselves as American as anyone else. It's notable that after Pearl Harbor Jeanne's father symbolically burns the Japanese flag. This is an expression of his loyalty and commitment to the United States, even though he's not an American citizen.
America had always been the land of opportunity for Papa. In comparison with his native Japan, where he toiled in the fields all day to make ends meet, it seemed like a veritable paradise, a place where you could carve out a piece for yourself. Once he'd arrived in America, Jeanne's Papa moved from job to job, hoping that one day he'd been able to say he'd made it big in America, thus restoring honor to the family name.
Yet Papa, like other Japanese immigrants, has been prevented by law from becoming an American citizen. US citizenship was actively denied to certain races, including immigrants from East Asia. This was largely a response to a groundswell of hostility towards East Asian immigrants, especially on the West Coast, where it was claimed that they undercut the wages of white workers. So despite Papa's commitment to making it in America, and his undoubted loyalty to the United States, he can never become a US citizen due to official racism and prejudice.