It will be a great disadvantage if you have Asian 
face and not knowing Japanese, this meaning they 
expect you to be able to speak Japanese, you will 
get to see their shocking/confused expression.

If you look different, for example non Asian, at 
least they expect you not knowing Japanese, 
sometime would actually atempt and try to 
communicate with you in English.

This is same for me, when I see an non Japanese 
speaking Asian I expect them to be able to 
understand Japanese, I be shocked if they talk to 
me in English with Asian face.