Many Japanese Americans volunteered to join the military in WW2. Did Japanese soldiers and civilians know about this, or was it kept secret by the government? Were these Japanese-Americans who volunteered seen as traitors before or after the war? And what attitudes did the Japanese have towards those soldiers?
Outside of perhaps the odd interpreter/intelligence analysis, Japanese-American's didn't participate in the Pacific theater WWII. Japanese-Americans who lived along the west coast were interred and later given an opportunity to volunteer to server in the Army (primarily) and were shipped over to Europe. There was concern among military and political figures as to rather the loyalty of Japanese-Americans could be trusted should they have fought in the Pacific theater (the service record of the 442 regiment would suggest these beliefs woefully unfounded).
So do to the lack of contact, Japanese probably didn't have much feelings toward Japanese-Americans. It would be interesting to see if the Japanese government used the interment of Japanese-American's as propaganda though.
Wiki page: http://en.wikipedia.org/wiki/Japanese_American_service_in_World_War_II