The Yamada family are sent to an internment camp. This was the experience of many Japanese-Americans during World War II. After the Japanese attack on Pearl Harbor in 1941 and America's subsequent entry into the war there was widespread hostility against Japanese-Americans, who were regarded by many as potential traitors despite the fact that the overwhelming majority of them were as loyal and patriotic as anyone.
In an outrageous denial of their constitutional rights Japanese-Americans were herded into camps far away from the strategically-important West coast, where it was feared that Imperial Japan would strike next. Conditions in these camps were appalling, with poor food and lack of proper toilet facilities. The people forced to live there under armed guard were treated like criminals despite being wholly innocent of any crime.
After the war, many of the camps's inmates returned to their homes. Ichiro is one of them. He's just been released from prison, where he's spent two years for dodging the draft. Before that, he'd spent another two years in an internment camp. Upon release, he makes his way to Seattle, where he moves in with his parents, who now run a grocery store in the city.