I recently watched Fury and noticed in one scene an Asian soldier among the Americans. His uniform was the same and he spoke English fine (only about one line, but still) so I assumed he was meant to be an American soldier. Now obviously the Americans weren't fighting against all of Asia but it just got me curious.
While in the US mainland Japanese immigrants and American citizens of Japanese ancestry were rounded up and put in detention facilities, their property seized, and their loyalty under question; there were a number of of American soldiers of Japanese ancestry.
The most famous, but not the only one, is the 442d Regimental Combat Team- which is still the highest decorated unit in US military history- so not only were Asian Americans present in the European theatre- they made something of a splash, earning some 18,000 individual awards over the course of the war. That particular unit; also known as "Go For Broke" was filled out by Nisei (second generation Japanese), many of whom were from the US Pacific territory of Hawaii (many others of whom volunteered to fight for the US even after their families and them had been moved to relocation camps).
Much has been written on this unit and there are a number good websites online that celebrate its accomplishments. In Hawaii they are still venerated and celebrated, though fewer and fewer email alive.