Which of the following nations was an Asian ally of Nazi Germany? China Japan Korea Manchuria

The Asian Ally of Nazi Germany was Japan.

You can remember this by remembering that the US was on the other side of the War than Germany : so every state that the US was against were likely in alliance with Germany - and Japan was both in alliance with Nazi Germany and in war with the US (think of Pearl Harbor and the atomic bomb - they're associated with US-Japan war during WW2)