how could they did that to you,its outrageous if i were you to bear that kinda discrimination,right.people did things which
might irritate you and even hurt your patriotic feeling,but you could chose to do the wise things,making positive reaction.
anyway,you are in Janpan,as long as things dont go too seriously,i think you should keep calm down.just remeber,why you are there?whats your purpose?keep doing your diligent work,in the near future,let Japanese approach you in a way totally differently,you probably could see fear in your staffs eyes.
Come on! Just work harder and ignore the prejudice from the Japanese, you didn't do it wellbecause you are not familiar with those things, I'm sure that you can do that perfectly in the near future, then you can tell them proudly,you are Chinese! The Japanese will respect you only when you show your abilities.:)